The tuned pipe just fits into the Aurora with uncut header. Distance from glow plug to first weld seam of the T-4010 pipe (I think Hatori´s #650 has shorter distance to baffle?) is a full 20" (510mm). Distance from pipe intake to first baffle is 12".

As per OS´s recommendation, this out-of-the-box setup would be starting point for 9.500rpm goal and a 12x11,5 prop.

So, I would expect to shorten the header pipe some 1-2" to result in approx 10.500rpm on ground.

Next questions for your advice:
- Pre-heat the engine before first fire-up by a powerful hairdryer? Is this a myth or worth doing it?
- Castor oil for first break-in period or same fuel as later for flight (synthetic oil)? This may be even more a question of beleive.

I made good experience by burning first half hour pure castor/methanol mix and then immediatly change for another 15min to my std. fuel (15% synthetic oil, 8% nitro) to get all castor residue out of the engine.

Some pics attached, thank you for your input.
Dominik