Never heard of them until you just mentioned. Looking on their site now but it's rather confusing. There's a 190 Cosworth upgrade for the Fez ST, yet doesn't involve exhaust?
http://pumabuild.com/pumacat/product_info.php?cPath=&products_id=1037Big price tag too.
My guess is that for proper tuning, you won't be Mountune. Otherwise you'd probably have seen/heard more about Pumabuild already
