GLHS exhaust system

[guzabri]

So ive got an 87 GLHS that i want to upgrade the exhaust on. I was thinking on going with the full 3 inch system from turbos unleashed with the test pipe they sell for the cat so it would be 3 inch from dp all the way back but from what i read i would need to upgrade my 2.25 dp to a 2.5 or 3.
Or i could keep stock dp and add 3" all the way back from there. The exhaust that is on it now has a few rust holes in it so it sounds bad, so i need to upgrade. Any suggestions on what i should do? Oh yeah the upgrades my GLHS has are stage 2 computer and a K & N air filter. Thanks

[glhman]

3" the whole way

[turbokid]

amen you want the best flow then 3" from sv back. our performance vendors sell a 3" sv.

[mwrenn]

If you really want it to flow and be a done deal, get the TU cast header, 3" swingvalve and downpipe, (the dp and sv are sold together) test pipe instead of the cat, then a 3" kit all the way back. Just a year ago a lot of this stuff wasn't available, thanks to TurbosUnleashed, it's an easy deal now.
I want to do the same to my Lancer, but I can only afford a section at a time. LOL

[The Pope]

remember though, that 3" doesn't reall fit an L body with a crappy rod shifter. So a 2.5" may be the way to go. With exhaust it is only as good as the smallest hole. Don't run a 2 1/4 into a 2 1/2 and then into 3" and expect anything. The header is nice, but not really needed unless you run a hybrid. Get a ported exhaust manifold and have it ceramic coated instead. Then buy the whole 3" system and I would add a 23.5" long race bullit Dynomax muffler instead of the test pipe. Or the fake cat on another thread if you need one to pass emissions. The TU header needs porting, I have pictures and an explanation coming lol.

[detobias]

no sense putting a 3" on an 87 with a stock 2.25" SV

IMO 3" arent worth the hassle, weight and cost on a mild motor, *especially* if you dont have a 3" SV ; with the $ you save, get a ported exh mani ; squeezing a 3" into an L-body is not easy and I have interference problems with my rear axle

look for a used 2.5" SV (89 TII only) or buy a new 2.5" SV ; get a 2.5" DP from any 89+ turbo car; then install the 2.5" mandrel system

UNLESS you plan to someday get a 3" SV & DP... then for now you should still look for a 2.5" DP & SV (you can always sell later), then use a 2.5 -> 3" cone to adapt it to the 3" 'cat-back' system from our vendors

hey, thats exactly what I did

[The Pope]

I like my 3" systems for different reasons too, sound and improved torque and response. With a 89 2.5" SV I gained .4 seconds and 4 MPH going to a 3" system on my GLHS. I never have liked the crack bang bang sound of the 2.5" exhaust. I like side exit too on an L body, I don't have the axle issue either though.

[detobias]

Quote:

Originally Posted by The Pope I like my 3" systems for different reasons too, sound and improved torque and response. With a 89 2.5" SV I gained .4 seconds and 4 MPH going to a 3" system on my GLHS.

WoW ! no other changes, rob ? or did you also change from a 2.5" cat & muff to a 3" cat & muff, or did you get rid of the cat &/or muff ?

I like my 3" too - it does sound great .. no cat or muff

but I guess I would be surprised if there was a significant backpressure difference on a mild-medium 2.2 *just* due to the pipes ... I can see there might be some gains in changing a whole 2.5" system with cat & muff to a 3" system with cat & muffs ... especially if the 2.5" cat &/or muff was particularly restrictive

[168glhs1986]

Don't buy the test pipe its way too small and is a waste of $$. Buy the 3" s.v., downpipe, the catback and a hi flow cat to tone it down. Also, the catback doesn't come with all the hangers needed, so unless you can weld, have it installed by a muffler shop. All great mods for performance and sound, you'll love it. To hear my 3" exhaust setup (with muffler), go to the vids section and click on my video, 1986 GLHS on the open road.

[The Pope]

Quote:

Originally Posted by detobias WoW ! no other changes, rob ? or did you also change from a 2.5" cat & muff to a 3" cat & muff, or did you get rid of the cat &/or muff ? I like my 3" too - it does sound great .. no cat or muff but I guess I would be surprised if there was a significant backpressure difference on a mild-medium 2.2 *just* due to the pipes ... I can see there might be some gains in changing a whole 2.5" system with cat & muff to a 3" system with cat & muffs ... especially if the 2.5" cat &/or muff was particularly restrictive

I had a 2.5 short system with just a cat for emissions and short 3" system with a 23.5" long muffler. The car is a stock setup with porting, stock valves. Ran the stage 2 MP computer and with my porting it detonated at 6 PSI part and full throttle pulling boost back to 10 PSI. I added +20s and it ran perfect. The difference was also seen with only 13 PSI on the computer, not with a boost controller. Both with pump and all season tires. Ran 14.4 then ran 13.9, ran 99 then 104. I sad 4 MPH because it was at least that much. 3" cats have the same flow as a 2.5" cat because they have the same core.

[guzabri]

so i ended up keeping the original sv(im kinda tight on money being 16 and all). Im gonna go with a 2.5 inch dp and 2.5 all the way back. The only problem is finding a setup that will work easily. FWD proformance sells a 2.5 kit but there is no flange and it starts 3 inches from turbo. so i dont want to have to build a flange and stuff so thats out of the picture. so i saw they have a 2.5 downpipe. They also have a 2.5 catback system. so heres where i need some advice. How much space is there between the end of the downpipe and where the catback system starts. i dont plan on running a cat. How long of a test pipe do i need for there or should i put a muffler there instead? Thanks for the help guys

[speedyshelby16]

Your not to far from me. You should see what I've got on my SC. 2.5" swing valve to a 2.5 flange 1/2'' it goes to 3" stainless to a 3" glass pack and then out the side with a daul 3" tips. Sounds awesome.

Not a great shot of the daul tips.



Way older closer shot


Also do you know there is another 87 glhs near you.