summit mufflers

I was always told the 40 series design was created by thrush and then flow master came along and dubbed it the 40 series under their branding. They are basically the same though.

I think thrush has been around since early 60's and flow master since early 80's maybe.

I'm not 100% on all that...i could be wrong....just saying.

Either way, I think they both sound good. I am also a fan of the hooker super comps, they have a real nice roar to them.