i have a hollowed cat with the twin loop and my car is silent like that of stock until WOP. When you look and huge 18 wheelers, SUV's, Trucks, Buses, etc, they are putting out sooooo much more polution then a little 4 banger. How is this selfish if we are trying to get a little better performance out of it ? I think, as long as it isn't shooting out shit out of the exhaust, and doesn't smell horrible, i find no problem. It's funny, that California has some of the most strict polution laws, etc, yet we have the worst pollution. Look at the pollution here compared to other major cities such as NYC, Chicago, Miami, etc. The laws in those states (besides NYC) are extremely lax compared to CA.

I say go for as long as it is indeed easily fixable incase you get reffed.