Which model Prowler do you have? Does it back fire on decel too? FYI, the BMP slip-on I put on my XTZ back fired on decel big time. It also ran SUPER hot, and I decided to go back to stock for the moment. I had read the XTZ is a bit rich when stock, but I no longer believe that. I think they are a bit lean from the factory. I ordered a fuel controller. Hopefully, this will address the lean condition. Also, I had a Speedwerx pipe on my 650 when I had it, and, after I rejetted the carb it ran great!