The No Cop Exhaust:
-3" piping (or whatever you need)
-Bullet or straight through mufflers, 1 to 2 for resonators
-Magnaflow or equivalent 3" inlet/oulet straight through muffler
-Hi Temp Black Paint
-Dont use a polished tip or anything
Bolt on. Enjoy.
95% guaranteed to ward off the five-oh. Workin on mine still, but you get the same gains, with probably less sound since the tip is 80mm same as the piping and not 115 or more like n1's and most import style exhausts, so it wont megaphone the noise coming out. and "shiny exhaust" = red flag to cops whether they can hear it or not.
plus you can sell the n1 and make the custom for 1/2 price of aftermarket 400-500$ systems.
if that doesnt work:
stock exhaust + mccord power plate/quicktech/etc electronic cutout before cat works best.
sorry to hear ur luck