I have a 97 MAX SE 5speed, I feel performace degradation after I have installed the peorformance LOUD Muffler, does it effect the pickup, I mean does it incease the peroformace. Any suggestion would be really appreciated.

 

it's a common misconception that having a freer flowing exhaust will cause the loss of backpressure and loss of torque. No such thing. however, there is a optimal exhaust size which will cuase the exhaust gases to exit the quickest.

Your loud muffler probably didnt' cause any loss in power.

 

some people seems to "feel" a performace degradation after changing to a louder exhaust. loud exhaust makes you "feel" your car is runing 50mph but actually running 30mph because of the sound. you press the gas pedal and "feel" it should run 50 mph due to the sound but actually you saw 30 mpg on your gauge. Thus, you "feel" a degration.
don't "feel"! get a dyno!