simex

I've got an 88 se and I took my car to the local performance exhaust shop so they could put on my new racing beat mufflers, and also put some high flow cats on. good thing i didn't order the entire cat back system because when they lifted up the car we noticed that there is a brand new Y pipe on there (bonus round). So anyway, the dudes at the shop suggested only switching one of the cats to high flow, because of the whole back-pressure activated aux ports (which i was impressed they new about). what do you guys think? will one high flow and RB mufflers leave me with enough back pressure? and how can i check to see if my aux ports are opening without taking it to a dyno and looking at them while someone else does a pull?

KingCobraV9

iTrader: (2)

the stock hedders have enough backpressure i think. if u have a catat all tho it will have more than enough. but keep 2 muflers man the car just looks bad w/ one it doesnt look as ballanced. it was designed for 2 so... keep 2.

91_fc

the 6th/5th ports on the S4's are activated by the amount of back pressure produced. there is a simple and cheap fix which is to simply hook it up to the air pump. then you go ahead and get the Racing Beat Headers and Prescilencer if you want.

WAYNE88N/A

I can tell you this- with a Bonez hi-flow cat (now gutted-don't ask), and the Racing Beat cat-back sytem, the aux ports WOULD NOT open when they were supposed to...A simple line rerouting to the air pump to ACV hose yielded more than enough pressure- I actually had to "tone it down" some 'cause they were opening at 3,000...But they work great now, and are solely dependant on engine rpm now, not backpressure...