I am currently with Noel Dazely have been for two years. When it came to renewal time they included a custom sports exhaust and a remap for no additional cost.
They were cheapest round by far for me (£600 rather than £1K+), just gone from a B5 S4 to a B7 S4 with AMD stage 3 and its £60 extra for the remaining 3 months on the policy.