Dual Exhaust/ Compression and HP loss??

Good Evening,
I'm pretty much building a show car out of my RS.. Due to the fact that I have the Bomber rear bumper, it would look better with the Dual exhaust..I want to have the exhaust build before I paint it.. I have a 4-1 aftermarket header, And i'm probably going to use the factory Cat (unless I can find a aftermarket. After the cat i'm going to y pipe the exhaust.. I wanted to do 2.5 inch pipe, but i'm worried about lossing the little power that I have. Now I don't know much about Compression and what not, but I know to much of an exhaust is bad for a N/T. So would I be lossing compression or hp if I go with a 2 1/4 or perhaps 2 inch?? Also, what kind of sound do you suppose I would get with this set up?

Dual exhaust on a N/T is just silly.

New bumper man, lol. JK

I would just run 2.5" to the y-pipe then like 2" to each muffler. As long as you keep the cat you will be fine. Bigger exhaust wont make you lose compression. It will mess with your exhaust gas velosity and that is what slows down your car.

Dual exhaust on a N/T is just silly.

For future reference, If your not going to be of any help, don't bother posting your un-related comment in my threads.. thanks. And like I said, its not for power gain purposes. I have the Bomber rear bumper which is built for a dual exhaust. So it will actually look nice on my car.

I would just run 2.5" to the y-pipe then like 2" to each muffler. As long as you keep the cat you will be fine. Bigger exhaust wont make you lose compression. It will mess with your exhaust gas velosity and that is what slows down your car.

Damn, do you know how much of a slow down I'm looking at?? As you know the 420A isn't that powerful to began with. This is mostly a show car, but I still would like to obtain the little bit of extra HP (and i do mean little) that I have gained from my basic mods. If you seriously think its beneficial to have only one exhaust, I can just by a different bumper OR do one exhaust with the bomber bumper which will look a little silly in my opinion. I just think the bumper looks really nice on my car.

The exhaust has no impact on the compression of the engine.

I agree with Silver on the size. You said this is going to be a show car right? So show, no go? If so, 2 1/4" to the y-pipe, then 2" back would be better. 2 1/2 may be too big for a car with no mods done. Either way you'll be fine though.

On a side note, make sure your mufflers are actually hanging properly. That's the thing that pisses me off the most is when people spend money to have duals, and then they're all cock-eyed and falling off. Lame.

For future reference, If your not going to be of any help, don't bother posting your un-related comment in my threads.. thanks. And like I said, its not for power gain purposes. I have the Bomber rear bumper which is built for a dual exhaust. So it will actually look nice on my car.

That wasn't an un-related comment. It's true. You get no gains from it, you actually lose power. It was being stated. If you want to keep the rear end and still have the gains, be a ricer and hang a second muffler in that spot. Seen that before. But that's the only way to have duals and not lose.

The exhaust has no impact on the compression of the engine.

I agree with Silver on the size. You said this is going to be a show car right? So show, no go? If so, 2 1/4" to the y-pipe, then 2" back would be better. 2 1/2 may be too big for a car with no mods done. Either way you'll be fine though.

On a side note, make sure your mufflers are actually hanging properly. That's the thing that pisses me off the most is when people spend money to have duals, and then they're all cock-eyed and falling off. Lame.

The only Mods I have is the 4-1 header and a CAI. But yea its just a car that'll turn a few heads. But I don't want to be moving in slow motion either. I just wanna get a heads up on how much power i'm looking to lose here and when am I'm going to suffer the most (low RPMS or high RPMS??). And if i'm going pay my hard earned $$$ to have this done, I'm gonna make sure it looks decent.

I believe I have a 420a also, and yes it is very slow. But what you dont understand is that as long as you keep your cat, your catback wont have a whole lot of effect on your car. The cat will give it enough restriction to keep from hurting the cars performance. Unless you go with some rediculous 3" pipe. 2.5" y-ed to 2" should be fine.

Your only going to loose bottom end to. Top end will increase.

That wasn't an un-related comment. It's true. You get no gains from it, you actually lose power. It was being stated. If you want to keep the rear end and still have the gains, be a ricer and hang a second muffler in that spot. Seen that before. But that's the only way to have duals and not lose.

LOL no thanks, my days of "ricing" have been gone for more than 4 years now. Along with the 1996 Plymouth Neon that I rice the hell out of.

I believe I have a 420a also, and yes it is very slow. But what you dont understand is that as long as you keep your cat, your catback wont have a whole lot of effect on your car. The cat will give it enough restriction to keep from hurting the cars performance. Unless you go with some rediculous 3" pipe. 2.5" y-ed to 2" should be fine.

Your only going to loose bottom end to. Top end will increase.

so basically I'm be a turtle from neutral to first and second to third??

so basically I'm be a turtle from neutral to first and second to third??

I don't understand this. Silver said lose lower end... in the powerband. Usually around 1500 - 3000 rpm or so you will lose, but maybe 5500 - 8000 you'll gain. Not gears... rpms.

I don't understand this. Silver said lose lower end... in the powerband. Usually around 1500 - 3000 rpm or so you will lose, but maybe 5500 - 8000 you'll gain. Not gears... rpms.

I don't drive my car past 5500 RPMS.. I might go up to 5000 if i'm not paying attention. Normally I shift arund 4000 maybe 4500. So like when i'm in less than 3000rpms, you'll hear my engine reving but I won't be moving?I'll be moving slow like that? Please bare with me, I don't know much about engine and power aspects.

Then you'll never feel any gained power. You'll have it drag a little more while driving though.

Then you'll never feel any gained power. You'll have it drag a little more while driving though.

Damn!!! Drag?? I can't deal with that, not in my eclipse.. My 4cyl dodge dakota drags like crazy. I can have the peddle all the way down to the ground and it still won't move any faster. I can't deal with that in my eclipse. no sir. Hmm.. I'ma have to think of what i'm going to do now.

Edit: So Could I just keep it at high RPMS than? My engine gets rather loud after 4500 RPMS (which is why I tend to shift by then). How safe is it to drive at 5500 to 6500?

Constant driving at those rpms is going to do damage. You usually want to keep the rpms lower when driving, but every now and then, like merging or whatever is fine. All cars are built to do that.

You wanna see drag, build your head with some cams and then feel the low end go right out the window. I had to change my driving style to accommodate for that. Power kicks in at 2300rpm.

LOL no thanks, my days of "ricing" have been gone for more than 4 years now.
But yet you want a dual exhaust to match up to your bodykit on a non-turbo dsm...

:disappoin

The dark ages are just beginning my friend...


**EDIT**
For future reference, If your not going to be of any help, don't bother posting your un-related comment in my threads.. thanks.
I guess I should post something related so I don't catch hell too...

And like I said, its not for power gain purposes. I have the Bomber rear bumper which is built for a dual exhaust. So it will actually look nice on my car.
If this is the case then you shouldn't care about gaining or losing bottom end power...

This is an open forum. If you don't care for people's comments, then too bad. If you want answers from certain people, a PM system is in place. My comment was not a direct attack at you, just stating my opinion.

It really doesn't hurt the motor at all as long as you dont just peg it on the rev limiter. I redline my motor a good bit, usally right past redline on the tach. Occasionally I pop the rev limited when I'm not paying attention but thats what its for, so you dont damage the motor.

But yet you want a dual exhaust to match up to your bodykit on a non-turbo dsm...

:disappoin

The dark ages are just beginning my friend...
So what do you suggest? Just do one exhaust?? Wouldn't that look a little stupid??

So what do you suggest? Just do one exhaust?? Wouldn't that look a little stupid??
What would look stupid is fitting something onto a vehicle that isn't supposed to be there... Doesn't anybody know anything about dual exhausts around here? Dual exhausts were originally fitted on high horsepower v-8's to help cut back on restriction problems... Tell me, do you really have a restriction problem on your 420a motor/exhaust? I really doubt it...

Any v-8 guy that see's a dual exhaust on it will pretty much give you shit about it. Stick with a single exhaust how its supposed to be... Unless you really don't give a shit about what people think cause you think it looks good... In which case you wouldn't be here asking our opinions on it...

If you can't accept a little constructive criticism from us then don't bother asking our opinion if your just gonna shoot down everything we bring up...

:disappoin

What would look stupid is fitting something onto a vehicle that isn't supposed to be there... Doesn't anybody know anything about dual exhausts around here? Dual exhausts were originally fitted on high horsepower v-8's to help cut back on restriction problems... Tell me, do you really have a restriction problem on your 420a motor/exhaust? I really doubt it...

Any v-8 guy that see's a dual exhaust on it will pretty much give you shit about it. Stick with a single exhaust how its supposed to be... Unless you really don't give a shit about what people think cause you think it looks good... In which case you wouldn't be here asking our opinions on it...

If you can't accept a little constructive criticism from us then don't bother asking our opinion if your just gonna shoot down everything we bring up...

:disappoin
Oh no, not the V8 guys and their gas guzzling engines lol.... So overall the dual exhaust isn't a good idea? So I guess i'm better off just sticking to the single exhaust than. It won't look that bad I guess. I could do a 2.5 with a single exhaust with no adverse side effects. Correct??

So overall the dual exhaust isn't a good idea? So I guess i'm better off just sticking to the single exhaust than. It won't look that bad I guess. I could do a 2.5 with a single exhaust with no adverse side effects. Correct??
Correct... If its such a big concern to how it looks, why don't you put some of that meshing stuff in to kind of hide the exhaust... You don't have to run the tailpipes clear out and through ya know...

Correct... If its such a big concern to how it looks, why don't you put some of that meshing stuff in to kind of hide the exhaust... You don't have to run the tailpipes clear out and through ya know...
I took a look at some cars on the net that had the same bumper. Ironicly most of them, if not all of em only had one exhaust and it actually looked decent. So yea I'll stick with the single exhaust. Thanks for the advice. Just save myself a couple hundred bucks :)I can use that towards my suspension! Now I just have to find a shop that does mandrel bends to customize me an exhaust.

EDIT: Damn, Now I can't find a shop that does mandrel bends. I called like 4 shops. Even shops that specialize in customs exhaust. They told me that if i'm going to use 2.5 inch pipe that the bends won't really effect the exhuast due to the size of the pipe. I was quoted around $250.00 to have it done from the cat back. Also should I enclude a resonater? Thats an extra $40.00. I'll have a silencer on the muffler.

It cost me 117 to have my exhaust bent. And no dont use a resonator

ever thought of just hanging a muffler on the other side? no duel exhaust, just another muffler? if its only for show... why not! cheap, and looks just as good... thats what i would do if i wanted duel exhaust on a 420a show car... :2cents:

Wow...can I have the last 5 minutes of my life back? This has to be the most ridiculous thread I've seen in awhile.

A Y-piped dual exhaust will NOT hurt performance, because you are not changing the initial exhaust velocity (commonly mistaken as backpressure) coming from the engine, all you are doing is splitting the difference of what flows through the muffler. Like silvr said, if you keep everything from your exhaust mani to the cat, your performance will remain the same.

On that note, it's your car, who gives a shit what other people think. I happen to think duals on an eclipse can look really nice, but ONLY IF it is done right. Don't go putting dual "dual tips" on so that it looks like you have 4 exhaust tips, cause that looks emo ghey, but if your bumper is made for duals, then go ahead and put them on if you want, don't let a bunch of people that will probably never see your car change your mind.

Gay !!! just like some one here put a fucking FLOWMASTER In their 1.8 eclipse. Due exhault on eclipse sound gay to me.:runaround:

Hey hey no call for that. That was 1999 when i did that and there were hardly any mods for the dsm's. Count the number of 1.8's with a flowmaster and the number of, i don't know, stock stangs for example. Originality being the keyword here. If u ask me it, sounds like a honduh, but i dont give a shit cause thats my gas saver, and my other cars a GSX. Maybe that should be my bumper sticker for the talon.

Anyway, I knew a guy with a 1g talon that had dual exhaust, and personally i liked it. Of course it was N/A and he wasn't too concerned about being quick, just looking good. I guess its all what you want out of the car.

cause that looks emo ghey
lol I love how you managed to get the words "emo" and "ghey" into this thread. :lol:

im gonna side on the single exhaust on this one.
with what you have done it wouldnt "hurt" per se your performance, it would give you a little more top end HP. if you go with single exhaust, dont go any bigger than 2.25. its the turbo motors that need the more freer flowing exhaust cause on those cars an increase in flow can actually help the turbo boost more. a friend of mine put duals on his hondurrrrr with the 2 tips that point up and its one of the ugliest things ive ever seen.

about the "just put another muffler there just hanging, thats gonna look funny to all the other "real car guys" when they ask why one muffler is black in the tip and the other isnt..... (ive seen people using spraypaint to correct this, kinda sad)

i have nothing against duals myself, they just have to be done right (being an owner of a 4cyl car with duals)