earlwb

What is your budget? What airplane to use it on? The budget is how much are you willing to spend for it. Some guys want the deluxe setup but they want it for next to nothing though. A tuned pipe can be fairly expensive by itself ($160 US is typical and you have to order it for the engine you want to use it on). The kind of airplane is whether it needs to be a rear exhaust or side exhaust engine. Also the engine displacement you are looking for. Some pattern planes like the Hangar 9 Phoenix for example works well with a OS .55 AX engine some large .61 engines may be too big to fit.