[naz]

i had a 4-1 header, high flow cat and 2.5" exhaust it was indeed very loud. i ditched the header after a few months, but you might like it who knows.

you should look around for a generic high flow cat.. i got a 'catco' high flow cat with 2.5" inlet and outlet and got it welded into the exhaust for $125 total.. i never tried to pass smog with it though so i can't tell you how it works from that standpoint