how much horsepower do i get for istalling a flomaster exhaust system in...

[Daniel]

...my 05 gmc sierra? 05 gmc sierra. 1500 stepside single cab. stock before the exhaust

 

[Molson02536]

Not much notice but it sounds good, it works best if you also install a performance intake and Dyno tune the ECM. You may find a lost of HP off the bottom end since you lost some back pressure which helps you get the HP on the bottom end, but if you get the intake system replaced with a less restriction system like a cold air system will get your engine to breath better. The ECM will compensate for that and will not need any tuning, but turning the Engine's ECM will make it a more noticeable difference and don't for get to have them tune your transmission too for firmness and shift points since your tuning the engine. Good luck and hope this helps.

 

[4_3_beast]

If it's on a 4.3, it makes a very noticeable difference...i have the flowmaster cat-back single outlet exhaust, with a volant CAI on my '05 reg. cab 1500, and it's a beast...