Have i been ripped off? PLZ HELP

ok, i went to a muffler shop and got a cat back exhaust system.(ansa silverline) now product sounds great!, but i feel NO performance gains. i am the type of person that would feel one hp, i felt nothing. i saw the mechaanic instal it. it is a straight pipe no centre muffler installation. now what i was thinking, for the pipe, he had a bunch of pipes laying around, he just picked one out and shaped it to fit my car, thus leading me to believe this is not a performance pipe what should i do? also the car is a little too loud will removing my k&n help? also i want a higher pitched noise i think when i had my regualr filter , since the car couldnt breath, it had a higer tone at 3k rpms am i right? Thank you all verry very much in advance

performance pipe? Really? Gains vary from car to car, but a pipes a pipe. What's the diamter of the exhaust? Also to get more out of it you may want to throw a intake on it.

i dont know, you see , my theory was that if the pipe is smaller than what the mufler can take, then youre not getting the most out of the muffler, other wise, i could of just installed a muffler on my old pipe.

measure the diameter of the pipe, if the pipe is the same size as the stock one and you have a different muffler, then you won't see much gains.

i dont know, you see , my theory was that if the pipe is smaller than what the mufler can take, then youre not getting the most out of the muffler, other wise, i could of just installed a muffler on my old pipe.
yea it is about the same diameter, that is why i am afriad ive been ripped off. also im running a straight pipe now, shouldnt i feel a gain from that?