Hey all. I installed my 3.5" mufflex (spintec muffler) catback today. I noticed that the car kinda lost some bottom end grunt. Admittedly I know there is a leak where the catback connects to the factory y-pipe/cat assembly. I just couldnt get the clamp around the reducer that came on the mufflex exhaust. Its supposed to collaps the tubing around the factory Y pipe apparently but i know this did not happen, and I can hear the leak under load on the freeway in a tall gear . Do you think the loss in low end grunt is because the 3.5" exhaust is too much for my car (SLP CAI, 4.10s)? Or do you think its the leak at the collector thats costing me so much bottom end?

Tomorrow i think im going to take it to a local muffler shop and see if they can weld it up properly. Ill be getting mac mids soon? Think that a custom Y pipe without cats into a 3.5 collector would be overkill? Just the thought of the Ypipe matching right into the diameter of the exhaust seems natural.. What do ya think?

Steve

 

It HAS to be from the leak. I barely noticed a low end loss even when I was driving with open long tubes.

 

Did you do a before/after dyno to prove your theory?

 

Ok took it to the local muffler shop today and they threw some welds on for me. The guy wasnt impressed with the fit of the mufflex, neither was I honestly during the install. Anyhow it seems like the power is back, it might just be me getting used to the car also. One nice thing is that closing the leak quieted the system down which is good because it was just a tad too loud for my taste. Everything seems to be in order now though.

 

Exhaust is overkill, but it shouldnt cause you a problem.

 

Your not losing ANY bottom end!

 

Werd. Get your buttometer checked ASAP.

 

You loose backpressure that is all. You are losing bottom end but your top end is much better. Kinda sucks but that is what you get for getting more HP. I just changed from 2.5 inch flowmaster to 3 inch borla. I raced a buddy of mine from a stop to about 100 he pulled me from the dig but at the end I walked him. It used to be backwards before the borla.

Tim

 

Do you have a LT4 knock module, or scanner to check your knock? sometimes the knock sensor picks up false knock from your now louder exhaust, causing you to lose a little power.

 

I don't think you lost any lowend the louder exhaust just makes you think you are further into the loud pedal than you are.