How much of a diference does a larger down pipe make?

[87BuickMan]

I still have the stock down pipe and Cat on my car, and was wondering if a 3" and a test pipe will be worth the $ ? Is there a seat of the pants difference? My Combo is .040 over 109 block 212 cam, fully ported stock heads, larger valves, 009 injectors, ported intake, stock turbo, Reds 93 chip, adj FP reg.
Now if there is a big diference, should I go with a 3" or a 3.5" down pipe?

 

[cool 84]

Ported heads/intake/cam, and stock DP and cat? I don't think I've ever seen anyone do it in that order. Going from stock to 3"DP and no cat makes a nice seat of the pants difference. It's safe to say that you just might feel a difference....

 

[BetMinesFaster]

I have to agree, you have done some airflow mods and your still blowing through the restrictive stock elbow, DP, and cat! Go 3" with a test pipe and you will feel it, should spool quicker for sure anyways!:biggrin:

 

[1986TR]

in just installed a 3.5 th style down pipe with the test pipe and WOW what a diff:biggrin:

 

[jhanson1750]

I could tell the diff with a stock long block when I installed a test pipe. I would say you would see quite a change in the spool on your car with a 3" DP and test pipe. Jon Hanson

 

[QUIP'6']

yes it will make a difference thats like making a marathon runner run with a sock over his head

 

[87BuickMan]

When I got the car it had the stock DP and cat on it with a Hooker exhaust. It still had the stock injectors and chip, and FP reg. Was thinking about having a 3" DP made up at my buddies shop. Would it be worth doing that without changing the elbow?

 

[stack1]

Chip upgrade might be in order also, it's nice to be able to tune your timing and fuel.

 

[jhanson1750]

If your talking about using the stock elbow and building a 3" from there I would say your wasting your time. It may help but I think the benifits would be minor. A true 3" DP is 3" from the mounting flange all the way out. I don't think the stock elbow even ported is worth the time. Just my opinion. Jon Hanson

 

[Project TNX]

Night and day, after you do it you're going to be kicking yourself in the a$$ for not doing it earlier.

 

[TLIMITED]

Night and day, after you do it you're going to be kicking yourself in the a$$ for not doing it earlier.

x2

 

[kh440]

in just installed a 3.5 th style down pipe with the test pipe and WOW what a diff:biggrin:

If you don't mind my asking: what combo are you running? (turbo and heads especially) Been wrestling with going with a 3 or stepping up to a 3.5.

 

[BADazzBUICK]

Spend the money and get a good 3" pipe,ITS WORTH IT!!!! Besides the alky,the best bang for the buck. You will really feel it with your combo The stock elbow was the worst part.

 

[SS_Sean]

yes it will make a difference thats like making a marathon runner run with a sock over his head

LOL!! :biggrin: :biggrin:

 

["Turbo-T"]

In my experience going from stock dp to 3 inch dp and straight shot exhaust meant gaining an extra 6 hp, spool up is still the same but car gained mid to upper end power and is faster mph wise.

 

[1of1547]

I think it is based more on your turbo size than anything else. I ran 11.08 with a TE60 and a ported elbow and a 2.5 ATR downpipe. Right now I have a 3.5" on my PT54 and basically gained nothing on the dyno over the 3" I was running before.

 

[Garycar]

There is no doubt that the 3" downpipe increases power over the stock downpipe. Years ago when we were running dump pipes into the fenderwell Terry Houston asked us to compare his stainless downpipe to the open fenderwell dump. His 3" downpipe worked equally as well. However, the question has come up repeatedly as to the difference between the 3" and 3 1/2" down pipes. Lots of speculation here and possibly some exaggeration. At some power level the 3.5" pipe would begin to prevail but honestly don't know what that point is.