E92 M3 Exhaust Options - sorry for another one

[Overhere]

OK, I know many of you have been there done it, I want to take all of the posts I've read and distill into a few key questions.

I deliberated for soooo long, and finally slapped down the cash, I picked up my M3 from Ridgeway in Salisbury a few weeks ago, what a great bunch,Ridgeway in Salisbury, among a huge group of arrogant BM dealers I've had the displeasure of dealing with.

So, as we all know, the sound is muted (I'm a TVR owner), I did think the coolest and safest option was the BMW sports exhaust option, the best I can get out of them is £2999.

For half that there is Miltek, Eisenmann, etc, I really don't want to go down the road of Akro.

1. My car is under factory warranty, does changing out the back box really effect that warranty?

2. I'm looking for an option which is not as tame as stock, but doesn't suffer from drone and is not unsociable,

As usual, I bow to your collective knowledge

Thanks as usual

JC