RE: Prop Suggestions OS 32SX
Buy a bag full of APC 8x8s.........!
If the engine isn't fully broken in, start off flying a few 8x7s until you're sure that the engine is dialed in good.
You will have loads of fun with this engine, plane and the exhaust system options that you have.
The tuned pipe will obviously improve rpm, look for about 18,000 with the 8x8 prop on 15% nitro.......but the difference in actual airspeed [vs stock exhaust], wont be stupendous.