2G 3" exhaust routing, problems

[eclipsegst3131]

hey i'm getting an exhaust system for my 2g gst and need to know. how big of the piping and how should i route the exhaust. i plan on doing low 13's so personally im looking for a 3". but some shops have said that if i go 3" then i have to route the exhaust under the axle. where as if i go above the axle then they have to supposedly bottle neck it to a smaller size when it passes above. i myself have no clue if this is actually true. so i need to know which way i can/should route it. also, is it the same on awd cars as well? just wanted to know for a future reference. thanks!

 

[arash15]

i got a full 3 inch exahust custom made at a muffler shop. its ok to go under the axle, awd has diffferent routing options because there is a transfercase and driveshaft as well as other things like the rear end.

 

[jim97gst]

Pretty much all off the shelf aftermarket 3" exhausts go under the rear axle/cross-member (no rear axle in your FWD). I think most 2.5" systems do as well. If you go with under, you will probably scrape now and again. I am lowered about 1 1/2" and have a 3" exhaust that goes under the rear cross-member, and it scrapes every once in a while. Just scrapes it a little bit though, no major damage. Doesn't scrape nearly as often as the front bumper or the RRE front lower tie bar. 2 1/2" exhaust will probably give you enough power to get into the low 13s. Exhaust size is not nearly as important as traction though with a FWD trying to get good ETs.

 

[98spyderboost]

3" fits just fine under there. There is a difference in the way a awd and fwd are routed tho. As you have a GST it shouldn't take a master machinist to make it all up. Whatever they were talking about "bottle necking" to go over the axle.... just isnt right. There isnt that much difference in 2.5 and 3" when trying to route it.

 

[DiamondStarM]

I have a full 3" on my tsi and it goes over the rear cross member like the stock exhaust. It has one spot that is flattened in a very little bit to make it fit, you can see where it would rub if it werent, but figure 3" is a pretty good size, so that small spot cant hurt too much if its not an all out race car. Also beware that if you get an exhaust that "bolts up to the stock downpipe" its probably flanged down to a smaller opening, so for mine to work with my 3" downpipe I had to get out the rotarty tool and gasket match the flange otherwise there would be a "lip".

 

[apgeclipsegsx]

people always ask me if my exhaust is falling off or somthing b/c i have the greddy evo2 and it goes under the rear axle....and the piping is HUGE

 

[lauj2gdsm]

i have custom 3 inch wich goes under my back axle and slanted back to rear exhaust exit . it looks very agressive.

 

[eclipsegst3131]

fyi, i'm gonna lower the car between 1.5-2" also. i'd rather it not scrape so...

in your opinion, what should I do (i'm not much of a good decisiion maker).

 

[lauj2gdsm]

home boy my car is 2.5 lowerd. and i have nerver scratch. just make sure that your pipe is no lower than your cross member by 2 inch. i had the same thought too, like it was going to scratch when i hit a lil bubmp. but if you are going from 1.5 to 2 inch i thing youll be fine.