guys I have a question that from time intrigues me, many of my friends have made the following change, in the final part of the barrel end (the final part where then comes out of the smoke) have executed the following things, mountain 50mm tubes and the final part had to be removed piece by 50mm and did weld a piece of smaller diameter if I'm not mistaken-or 40-0 45mm, with the effect of the strong whiff of each accelerated type of an air compressor and performance a p? torque under why? increases the back-pressure, but this what the f? well to the turbine or engine? or create the damage in the long run, thanks a lot