James, my two cent, I had a P4SS and let convert her to LHD. I enjoyed her a lot but got rid of the noise level after 23K km. As you have a RHD car the noise level will be much more comfortable (but when sitting at the left like me, the TBs are much sharper to the ears).
The second reason I sold her were my worries about the first TÜV (MOT) which would have been only to pass with the "help" of "friends". Reason was, there is no OBD2 on board (which is obligatory for Euro5/German TÜV pass), and also she is much too loud (when getting measured by police) etc.
I would go for her again, if the above mentioned issues were not existing, at least in Germany. Especially since the ECU upgrade is available. This benefit I could not experience at the time. I was fine regarding the power but the smells of exhaust were too much.
One recommendation, if you want to own one of this breed. As you will absolutely love her and her performance, there is one issue which should be addressed: The rims, for two reasons. First, at least on my car they were notched at the inside to a dangerous point. Secondly, the wheels are way too heavy (including the adapter). I would buy a P4SS if I were you, but I would swap the wheels for something similar to the ARP4 wheels, made by Image-Wheels.
