In the very near future i will be adding a 2 1/2" ss atr exhaust system to my buick along with gutting the cat ( fyi cat is stock). Here is my question do the 3" downpipes that are out there line up and bolt right to the stock cat or do i have to either go with a different cat or a race pipe? Secondly, although I know that the terry houston pipe seems the most popular, how would i fare if i was to use say the 2 piece pipe that postons or some other venders offer? I am on a limited budget, that is why i am considering this route other than the THDP. Thanks for any suggestions. (If it is needed, the downpipe would be coming off a TA-49 turbo.)
3" downpipe
- Thread starter artmonet
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TR Custom Parts
Mark Hueffman - Owner
- Joined
- May 25, 2001
- Messages
- 12,733
When I first got my GN back in 95 I went with the Kirban 2 piece downpipe and used his cat that went with it. Stock size cat is 2.5" I believe and won't fit the 3" downpipe without a reducer, (talking about the Kirban dp) If you go with the TH downpipe as I did this year you will have to use his cat or test pipe as they are real short and made for use with his pipe.
If you are on a real budget you can't go wrong using the Kirban or Postons pipe, just use their cat or test pipe.
If you are on a real budget you can't go wrong using the Kirban or Postons pipe, just use their cat or test pipe.
salvageV6
Daily Driver
- Joined
- May 25, 2001
- Messages
- 20,988
3" Cat. is needed. I gutted the one that came with my THDP and picked up 4 psi. boost. I think that cat. kinda sucked.
I am going with my 3" Mease downpipe and a 3" expensive Random Tech. cat. on the more stock GN. It is going on next week in place of the stock cat.
Still have the stock muffler system but I think I might pick up a coupla psi. anyway.
I am going with my 3" Mease downpipe and a 3" expensive Random Tech. cat. on the more stock GN. It is going on next week in place of the stock cat.
Still have the stock muffler system but I think I might pick up a coupla psi. anyway.
Why not go with a Hooker catback 2.5" exhaust instead of the ATR and with the money you save you can put it towards a THDP?
The Kirban or Poston's 3"DP along with a ported elbow work just fine but the THDP is better IMO. I have used both and once you start getting up into the turbo's that are larger than a TA49 I feel you need ot go with a THDPanyways since the stock elbow won't flow enough for larger turbo's.
The Kirban or Poston's 3"DP along with a ported elbow work just fine but the THDP is better IMO. I have used both and once you start getting up into the turbo's that are larger than a TA49 I feel you need ot go with a THDPanyways since the stock elbow won't flow enough for larger turbo's.
Dan Thompson
New Member
- Joined
- May 25, 2001
- Messages
- 778
I maybe way off on this but I though the stock elbow and DP was good to go into the low 12's. A stock elbow can be cleaned up and help some, but do you think you will see much of an increase in performance over the stock DP with the mods you have now?
If you look at http://www.gnttype.org/techarea/recipes/recipe.html
the downpipe is added after he achieved 12.28 1/4 mile et.
If you look at http://www.gnttype.org/techarea/recipes/recipe.html
the downpipe is added after he achieved 12.28 1/4 mile et.
I went 11.8's with a 2.5" ATR stock replacement downpipe/ported elbow/TA49/Big neck stock intercooler/Bluetops, thru the exhaust on drag radials and only went, .05/1.5 mph (Average of 3 runs) faster switching to a THDP with everything else the same.
A larger downpipe seems to help the above 5000 RPM pull, but overall ET was very close.
A larger downpipe seems to help the above 5000 RPM pull, but overall ET was very close.
