We have already seen that some tuners tried to reduce the diameter of the exhaust pipe on two-stroke SX-R in order to increase the back pressure, raise the rpm and make better the overall performance. Well, on the other hand a company from Japan, Motoine Raicing has tried to relief the exhaust pressure on the same two-stroke engine by adding a relief pressure to the exhaust stinger. We do not know how does this modifications alters the overall performance but at least is a different approach. We have seen expansion and relied boxes on other type of exhaust systems in the past.
