Does the reduced backpressure from an aftermarket y-pipe affect when/how the special valve in the Maxima's stock muffler closes/opens? Does it affect performance in any way?

I'm guessing it does, but would like to hear from others.

 

I have a 2k1 muffler on my 97.. and both valves are open at like 2500 rpm's

I have a budget y-pipe and custom 2.5 inch mandrel bent cat back with no resonators

I switched from a dynomax muffler, due to the noise, and I lost 1 HP and 4 lbs TQ

but if you keep the 2000+ factory muffler and add an aftermarket exhaust/y-pipie I do not think there would be any performance loss that you would have.

only if you changed your muffler to a NON- high flow muffler should you lose any performance