I've had two exhaust shops so far try to talk me out of switching to the Magnaflows... They both told me that there is no performance gain going from the stock cats to the Maggies. Not sure if they just don't want to mess with it or what.

 

Nice upgrade. You'll love that exhaust.

 

I think personally, they don't want to mess with it. Maybe b/c there is very little room to weld them the right way? Just a thought. Some say, I think DarrenWS6 said this, in '06 that Ford changed the design to a more "free flowing" converters. I think there was a thread over in the '09-'11 truck section. It would be nice to see ya get dynatech longtubes with their cats. But that particular kit, money is a whole other story, which I understand.