on a car with a like for like setup, would a side exit exhaust have detrimental effect on performance against a car with a conventional exhaust that's been setup on the rollers. also would an mfi car be sensitive to such a change regards fuelling? the idea is for a sleeper and from the rear a 4'' mongoose poking out the rear kind of gives the game away.

 

Depends on bore sizes etc... sideys normally used on racecars for full flow under full throttle a conventional will give better back pressure and quieter

 

Surely you could just possition the back box closer to the chassis and have a 90 degree bend tailpipe facing down behind the bumper?

If you are going for a sleeper I dont think a side exit will help.