Enhancements?

[reese]

I apologize in advance if this has been covered, as I am sure it has.  I recently bought a 2002 Sierra Denali and am interested in putting in a K&N air filter and maybe a catback system.  My questions are: How much will these items affect my mileage?  How much more power can be expected?  Is there an aftermarket exhaust system out there that retains the look of the OEM exhaust?

[CMNTMXR81]

1) Usually by a little bit as your engine now becomes more efficient as it doesn't have to work as hard to inhale and exhale as it did stock.

 

2) Gains vary from vehicle to vehicle, engine to engine.  Can't give you an accurate answer.  Your best bet would be to dyno the vehicle before, then dyno it after to give the most accurate repsonse.

 

3) Yes and No.  Most aftermarket pre-fabbed units follow the same routing as the stock unit.  The aftermarket unit is simply more efficient at doing it's job.  It's when you start fabbing your own custom systems that it won't resemble anything stock.  A good exhaust shop can make it look any way you want it.  From flashy to even cutting the stock tailpipe/tip off and re-installing it on your aftermarket unit.