max power with 4" exhaust ??

[xcablb7]

At what point does 4" become a restriction ? I'm running a 5 " downpipe right now and have a 4" muffler and tailpipe, got to many other things going on to drop $500 on exhaust right now but how much if any power will the 4" steal? I'm thinking pretty minimal but has anyone ever done a beforew and after ? Or made 900 with a 4" kit ?

 

[GeneralTJI]

Man you can move a lot through a 4" pipe before it becomes a noticeable restriction. I don't have any data to chime in with although I can say as the exhaust travels down the pipe it's cooling off (shrinking...in theory not needing as large of a pipe)... if your pipe transitions smoothly from the 5" downpipe to the 4" it probably isn't hurting flow much....

 

[blk smoke lb7]

Great question:thumb:

 

[xcablb7]

Anyone else have any input ??

 

[770JOHNNYW]

mine changes from 5'' to 4'' at about the 2nd door on my crew cab...i bet you wouldnt see any difference and it would just be louder. mine is very quiet with the twins and a muffler makes highway crusies pleasent:thumb:

 

[hondarider552]

I dont think we spin enough rpm to see any restriction post turbo.

 

[Jscherbs]

At what point does 4" become a restriction ? I'm running a 5 " downpipe right now and have a 4" muffler and tailpipe, got to many other things going on to drop $500 on exhaust right now but how much if any power will the 4" steal? I'm thinking pretty minimal but has anyone ever done a beforew and after ? Or made 900 with a 4" kit ?

You could always weld a 4 inch flange onto the end if the exhaust housing and just run complete 4 in exhaust

 

[xcablb7]

I don't want to get rid of the 5" downpipe just didn't want to stuff a cork in it by putting on the 4" muffler and tail, I have a reducer and all the band clamps so I'm just gonna throw it on and hope for the best maybe make it easy to disconnect and dyno it with and without