When i bought my 88 GXL the previous owner had a 2 1/4" manifold to Y straight pipe put in ( custom ) to a ebay N1 style muffler on either side. even with a cat put in this set up is very loud ( well at least to the parents of my girlfriend late at night ) and I was wondering how quiet the racing beat NA cat back system is, i suppose because the front half of my exhaust is custom i'll have to get the pre cat silencer and all that to.
Or does anyone else know of any other relatively quiet cat back systems that still give you decent power?

 

RB cat back is quite and i have it with 3 inch staight pip from the header to the cat back and its not so loud that any1 would complain