3" exhaust is not too big. Maybe with a random technologies cat...but really they only flow about 200 more cfm than a high flow magnaflow cat. I saw a nice decent improvement on my 3" exhaust on my old ZJ, it sounded AMAZING, and i increased 2mpg after all the stuff I did to it. Not saying that mpg gains are a goal with jeeps....but just stating results I saw after everything my ZJ went through.
1998 ZJ Laredo, 4.0L, 2WD, it's boring