Back box delete in London?

[Mht3030]

Hello all!

Been driving my C7 RS6 for a few weeks now - as much as I love it, the stock exhaust is ****
Don't really want to spend huge money on a custom exhaust just yet - so was hoping to do a back box (muffler delete) can anyone recommend any good places in London or surrounding areas who could do it at a reasonable price? Found a few places charging a bit too much. Any advice on what I should be paying?

[C5Avant]

I have been recommended Hayward & Scott, based in Essex. Might be worth a call.