Catback

If I plan to upgrade my turbo (probably just to the big 16G EVO III) do I need to wait on getting a catback because of different sizes or would it work on the new charger also? If it is okay to get it now, who makes the best ones? :confused:

A catback exhaust will work with any turbo app. And as for the best ones, i say get the one that best fits your budget. Not to cheap. Not overly expensive.

Yea, don't get a 16g without good supporting mods. Won't run like it should. If you are good at fabrication, the exhaust route for the gst only requires a minimal amount of bends, so you could make your own exhaust for very little money.

Do a LOT of research before you put in the 16g

If money is not a problem , I say go with some full titanium exhaust, or some buscher exhaust....they specialize in evo/dsm's.....not sure if they have titanium tho...

So the GReddy or 5 Zigen stainless steel isn't a good idea if I intend to upgrade?

Most catback exhaust systems are designed to work with a larger cat or downpipe. That would mean custom fabrication or a little adapter to attach it to your stock cat. If the catback system comes ready to attach to your stock cat, it won't work well with an upgraded downpipe. If you want the 16g you'll need full exhaust, turbo back. If you can afford to buy both the dp and the catback together, you should.

I'd go three inch, so you leave room for future upgrades. Mandrel bent is good. Aluminized (sp) is cheapest, titanium is the most expensive. As long as it doesn't rust, I don't see the difference. I doubt titanium is much lighter, does anyone have those stats? Think about whether or not you want to run a cat.

The brands you mentioned are probably fine. The most common exhausts are the apexi n1 or custom from a dsm-specific vendor. Personally, I have a apexi n1 with a dp on the way from Road Race Engineering. The cheapest solution would be to have a custom exhaust made for you by a friend or shop. It'll still sound good :)

Keep your budget in mind. With a few things in mind (weld quality, flex section quality, sound quality, rust resistance, mandrel bending, etc), one pipe is as good as another, so it's probably best to save your money as much as possible.

I wouldn't do a catback until you are ready to go full turboback. If you did... you would use a reducer to mate with the stock cat, and the turbo wouldn't matter of course. I can't take seriously anyone who recommends titanium exhaust.

Yea, its always easier to get a turboback all at once...less of a hassle. Both greddy and 5zigen are good exhausts, but get a DP and cat at the same time so you dont have to stress about it later. Without the better flow from the DP and cat, the catback exhaust won't really be at its best.

You said (hooptie) I should get a dp when I get the catback, will I still need the adapter until I upgrade the turbo?

You said (hooptie) I should get a dp when I get the catback, will I still need the adapter until I upgrade the turbo?

The upgraded dp and catback will bolt to your stock o2 housing (like the stock exhaust does), so you'll be fine. No adapter needed.

Turbo - o2 housing - downpipe - cat - catback - muffler

(turboback exhaust is enlargening what's behind the turbo, catback exhaust is enlargening what's behind the cat)

Turbo to o2 housing, 4 bolts.
o2 housing to downpipe, 2 bolts
downpipe to cat, 2 bolts
cat to catback, 2 bolts
catback to muffler, 2 bolts

The stock exhaust at it's smallest point "is reportedly 1 7/8" (95_gsxracer). So picture a hole that size with a flange around it, attached by two bolts 180 degrees apart, to the same. This is hard to describe, look at this :) http://www.roadraceengineering.com/parts/dp/rredp-2gawd-options.jpg Anyway, the idea is that with the same size pipe, the bolts on the flanges match up. A 2.5 or 3" catback will have a larger flange for its larger size, and the bolt holes on the flanges won't match stock pieces.

Some companies make catback systems that constrict to the stock exhaust size at the last moment so they'll bolt up. If you ever get a downpipe in 2.5 or 3" size, hoping to upgrade, you won't be able to bolt up to the smaller flange of the catback that allowed it to attach to your stock cat. They sell bolt on adapter pieces to get away from this problem. It's a very short piece of pipe with flanges of the two sizes welded at either end. Again, this works for trying to attach a catback to a stock cat, say. Some exhaust systems come predesigned with this piece, so that you can attach it to your stock cat without problem, then upgrade without problem. Apexi is the only system that does this that I know of, and I searched before I bought.

Think about whether or not you'll run a high flow cat or test pipe. The high flow cat is kinda illegal, the test pipe is less environmentally conscious and illegal, too, but red states seem lax about this law. A test pipe is better for performance. Same picture I posted above, you can see the differece http://www.roadraceengineering.com/parts/dp/rredp-2gawd-options.jpg. They call the test pipe a race pipe, same thing. You also have the option to eliminate the cat althogether, which is what most dp's do. For spacial orientation, the race pipe/high flow cat is oriented where the stock cat would be. Btw, I'm not trying to encourage rre. At least, not until they start giving me kickbacks for it :biggrin:

Sooner or later, the exhaust has to slim back down to stock size, since it has to attach to the same turbo. The longer the larger it is the better. Within constraints of size limitations, money, and weight. There are different ideas about low end torque lost by exhaust too large, but I haven't heard one of those arguments recently. The argument about exhaust flow velocity as it applies to na but not to turbo engines, and all the other technical stuff, deserves it own post (from someone who knows more about it than me). Bottom line of each of those arguments, get three inch anyway.

Using the logic directly above, you can change the o2 housing. It may not be worth the money, your call. It helps creep and by nature of being larger develops less backpressure; how much so is debatable. Unless you're upgrading to the evo housing, which has a little different angle, stock and aftermarket downpipes will all fit on to all o2 housings.

Don't know how much of this you didn't know, or wanted to know, but that cover some big points. If I said something wrong, someone please correct me.

Yea that helps a lot. Thanks