Can anyone describe what effect on performance decreasing the overall length of the exhaust system would have? I believe this would make it resonate at a lower frequency, but don't know anything about what it does to engine tuning...
I'm thinking about shortening the tail pipe on my f150 so it exits in front of the rear tire.
J

 

Somebody correct me if I'm wrong, but for the most part, you will see absolutely no performance variance just by shortening the tailpipe. The main thing that affects your truck's performance is width/diameter of the exhaust as it relates to airflow or backpressure.

 

Both the pipe length and the pipe diameter can influence backpressure. Bear in mind, though, that in gas engines, "less backpressure" does not equal "better" all the way down to zero. Unless you have reason to believe your engine is suffering due to excessive back pressure, you don't necessarily want to fool with the exhaust system.

The above is not true of diesel engines (less *is* better for practical purposes).