Currently debating the mid silencer delete on mine - it's like an on going 6 month long debate of mine haha mostly cos of invalidating the warranty. Loads of posts on here about it, but basically I've been quoted £220 by EMP to have it done which I understand is about right although I'm sure someone will come along and say they paid a lot less ....
I can't comment on other exhausts but I've mostly looked at miltek non resonated, the black cerakote tips seem to be popular!