Thanks for that guys, as always a big help. Yip it's going to be a custom fabricated exhaust, and the guy has had a look and knows it will be tight, but he reckons he can hack it - Battery box is the worry.
And thanks JamJay, I have emailed them awaiting a reply on a quote. Been looking everywhere for someone who will sell me just a diffuser. Although, I know I am going to be paying Hartge prices for Hartge quality!
Regards to you all