I've heard the slp, cherry bombs, borla, custom mufflers, you name it. I loved the borla cat back. Had the best sound no rasp, even better when I went turbo. I have the zzp on my impala currently, superchargered not turbo, and it sounds ok, it's quiet at idle and gets louder when you accelerate but I have to get my exhaust connections welded up, in sick of leaks from the downpipe connections, 2 bolt flanges are dumb! If I did it again it go maderal bends to borla mufflers with a small res.