Exhaust question

[70Firebird/TTA]

How much real HP/Torque gains are we looking at if we install one of those "custom" 3 inch exhaust systems with a free flow cat? How many tenths is such a mod worth on the 1/4 mile. Since the car already has a good flowing exhaust..I want to spend the $$$ where it is most advantageous.

Thanks for your knowledge/wisdom fellow TTAers'

 

[TT/Ameasap]

I have heard 30-40 hp but you would have to see what we all agree on HTH

 

[RobR]

I think getting rid of the cat is close to 30HP by itself. If you were to get a high flow cat and cat-back, I would guess 20-30HP.

 

[Kyle F]

Well in my personal opinion removing the cat is probably only worth about 10-15hp, then a free flowing exhaust is another 10-15hp.
I think the Turbo Buick powered cars respond better and have more of a feeling of power because of faster spool up. This means more boost in the lower rpms due to the increase in exhaust gas velocity and lower back pressure behinmd the turbo. The combustion chambers feel no loss of back pressure because even with an open exhaust the Turbo will provide the back pressure on the engine.
I think that, with out any dyno sheets to prove it, the power increase is wide and across the board rather than something like 40 peak HP.

 

[Grumpy]

get rid of the cat an leave the stock exhaust alone an do other simple mods