The E60 headers are the MAJOR restriction AND the biggest power to gain if done correctly. To get to Z06/997TT level all you really need is a de-catted header and exhaust. If you buy catted headers, you might as well keep the stock ones and send me the $4000 to my personal bank account, is the same result, money lost.
Headers are not a bad mod, actually there the best mod to these cars, of course done the right way.
:cheers:
P.S. I miss my tank a LOT! :Thumbdown: