I have stock manifolds on my car and at 130,xxx miles i am wondering if maybe my cat is becoming clogged. Is this a fair concern and if it is clogged i want to replace it with a straight through pipe (off-road) can i have any custom exhaust shop make one if i give them the length and pipe diameters? or do i have to pay the 120 dollars that thunder perfomance wants for there pipe. Also, i am aware that no shop will install an off road pipe but i dont see where they wouldn't be able to "make" one.

 

Dont know about where you live but emissions are strict here and the shops will still do custom work. You just tell them its for show and your car is exempt for that reason if they get weird about it.

 

It may be the same price to get the pipe from thunder and it would look better. May as well ask an exhaust place though.