I had a japspeed like that and as ZEUS has said there can be fitment issues. I ended up with a poor fitting one, put up with it for awhile but got rid in the end. Depending on your budget next step up would be a cobra or a scorpion Between £450/£500. Though with that you get the centre pipe aswell, so a y pipe back system.
I see your in Nottingham so it's worth sending Mitz@cougarstore a PM