question on exhuast

Hi all. I just recently bought a 90 lx 5 spd stock bore size, but with E cam, high vol oil pump, heavy duty motorsport clutch, 373 posi, cold air intake, upgraded max sensor housing, msd ignition and blaster coil, the car has bbk shotry headers , h pipe with high flow cats and mac mufflers, all 2.5 in. The car sounds pretty good but i want it to really roar. I was looking into the flowmaster cat back american thunder 2.5 in system with the 40 series delta flow mufflers. Will that be louder, and will it perform as well. Iwas also looking into the flowmaster 3 inch header back system with super 40 mufflers and x pipe, no cats(i realize this is a racing only application, but id be willing to switch it out once a year for emmissions purposes), but it says the 3 inch system works well on modified 5.0s. Looking at the list of stuff I have does it warrant a 3 inch system, or will it be too much? I dont want to lose performance. Or the 2,5 inch be loud enough, or is there another system like borla or magnaflow that is wilder, im kinda new to the game so im a little unsure of what works best. Sorry for the rambling on, but any help would be great. Thanks

3" systems are excellent. The flowmasters sound great on Mustangs. It depends on how much power you want to make (in terms of going 2.5 vs 3" for exhaust). For example, in the F-bodies, a 2.5" system will only support around 400 hp. Anything above that will start to get choked. Good luck with your decision.

thx junkie. I was told that a 3 inch system is too big for my car. im Not that much of an expert, so do you think with my mods ist ovekill or not?

The 3" systems work well with modded 5.0s. I know many running 3" catback systems. Hell there are close to stock F-bodies running some 4" catbacks. You have a cam and when you go with headers you'll definitely need the 3".

the again f bodies are only running single exhaust, i wuld go up to 3in until about 500hp, until them, 2.5 is just fine

But many F-bodies (including myself) are now running true duals. 2.5" True duals choke too much power above 400.

what's up all!! I've got a ???? how much work would it be to turn my mustang coupe into a fastback!!?? halp appreciated

i am going to go out on a limb here and estimate that it would be cheaper to buy a second fastback donor car and have the bodies swapped than to have the rear of your car re-worked.

in the future go ahead and start a new thread for your questions and post more information. i assume that you are talking about a fox, but i guess you could be interested in converting any pony.

I have delta 40s with long tube headers off road h-pipe the exhust is all 2.5 they are dump plus little motor work done they roar when u lay down the gas.

the again f bodies are only running single exhaust, i wuld go up to 3in until about 500hp, until them, 2.5 is just fine


I agree, 3 in. tips are all good, but stick with dual 2.5" for most of the sysem for a bolt-on car. Remember you have almost 50 less cubic inches than an F-body...

Start with the X or H pipe and go from there, MAC Flowpaths are pretty darn loud when catless. An H will give a throatier rumble than an X BTW...

the again f bodies are only running single exhaust, i wuld go up to 3in until about 500hp, until them, 2.5 is just fine


My 90lx is a 5.0. It has dual exhaust. Did any 5.0's come from the factory with single exhaust? thought they all came with dual?

thought they all came with dual?

They did.

Anyway, if you want your car to be loud just take the mufflers out and have straight pipes.

79/85 are all single, they can be made dual if you use the correct transmission crossmember

79/85 are all single, they can be made dual if you use the correct transmission crossmember
My friend has a '84 firebird and exhaust is his setback. We built a 1970 350 2 bolt main for it. Ported stock heads, Performer RPM intake and the matching Edelbrock hydraulic flat tap cam, 10.2:1 compression, ect ect. I built a TH350 to go behind it and we think he has 4.11 gears, not for sure on that though.
What tranny crossmember does he need for duals? We where thinking of maybe notching the subframes and running sidepipes then reinforcing the subframes.

i meant 79/85 stangs, if you want to convert those you need the double hump crossmember, its the same one the 86/93 use. i know nothing about firebirds, though