For model year 2000 the exhaust system might be a little less restrictive
but for the model year 1995 Ram 1500 systems
the peak backpressure is about 7 psi at full throttle and 4000 rpm.

Kenne Bell claims that with the exhaust disconnected behind the catalytic converter on a 1998 model they measured about a 5% gain on a 5.9V8:

http://www.kennebell.net/techinfo/do...-test-data.pdf

 

A stock muffler flows well.. and with these so called long stock mufflers , my stock muffler is only 22 " long 18" case just 2" longer then most performance muffler