Well 2.5" is a bit large for your setup. You'd want that if you were turbo or something a bit more extreme than an intake.
This is probably what he meant by "not heavily tuned"
Stick with 2 or 2.25. Not sure what muffer you got but you can either exchange that one for a smaller inlet or get the shop to put on a reducer.
Hope that was some help but he's right, too much backpressure isn't good. I wouldn't stick with OEM size tho, it is very small. I went with the 2.25 and all is well after 2 years. It definitely helped performance and fuel economy went up a bit too.
This is probably what he meant by "not heavily tuned"
Stick with 2 or 2.25. Not sure what muffer you got but you can either exchange that one for a smaller inlet or get the shop to put on a reducer.
Hope that was some help but he's right, too much backpressure isn't good. I wouldn't stick with OEM size tho, it is very small. I went with the 2.25 and all is well after 2 years. It definitely helped performance and fuel economy went up a bit too.