Everyone needs to calm down. These are just mufflers and no matter how you want to put it, you're not going to realize huge gains. Stop beating a dead horse.
I put these mufflers on last night, took about an 1.5 hrs and I am very satisfied. Yes, they are custom and don't have the cleanest of welds - In fact, I wasn't even impressed. But installed, they look better than stock, and sound great.
Overall, these are a good, cheap alternative to having your Z4 M sound like an actual sports car without the ridiculous price of an SS, Eisenmann, or whatever muffler. I will say, ~ $600 is still considered an exhorbitant price for a pair of cans in my book, but $1000+ is just stupid money for marginal gain. Obviously the economies aren't there for the Z4 M market, so I get that - but seriously?
Aside, I rarely chime in so I thought I would... Enjoy the exhaust GB'ers
