MIJ Performance = NO NO NO Not ever!
John Ashley Walsall = Yes, workmanships good and he's a straight bloke.
TopGear Great Bridge = Yes, Been using them for years on all of my cars!
Powerflow Stafford = They built the system on my 172 before i owned it. Every exhaust builder who has looked at it has picked it apart for the way it's made.
Alex, try TopGear or John Ashley. Custom exhausts usually fit better than off the shelf stuff.