TRX 3.3's last just fine. I think almost all rod failures in the TRX engines are due to operator error. I've ran several TRX engines over the years, including 3 3.3's and not one of them has thrown a rod or bearings. One of them has over 6 gallons on the factory bearings, conrod, piston and liner, and pull starter even.

40% nitro is a bit much for how the 3.3 is shimmed - you'd want another head shim or two for it to last on that much nitro even at the high elevation. If that is all you have access to, keep it a little richer and let 'er buck. Get it running, get it hot, and run it. If you baby it, run it sloppy rich, and follow Traxxas's break-in 'suggestions', you will likely encounter a rod failure.

Just my opinion.