My 97 has a replacment muffler and tail pipe. The p.o. just had 3" pipe welded in to the 4" oulet of the cat with a flowmaster muffler. How much of a restriction is this causing, going from 4" back to 3"? There's nothing wrong with the tail pipe and muffler. Should I wait till it needs to be replaced again or do you think it's causing a significant restriction?

Thanx

John F

 

the flowmaster is a significant restriction... replace it with a straight through muffler (or piece of pipe hehehe) and watch the turbo spool up considerably quicker and EGT's go down

 

My truck has the stock 3" pipe from the turbo that goes back to the mid cab area, then it goes to 4". It has an 4" in and out (unknown name) muffler and 4" tailpipe. Would a four inch downpipe and straight pipe make that much difference?

 

depends... if the muffler is straight through w/ no baffles, removing it probably won't do much, but it'll sure sound better