Guys

as promised a little report on my N21R's first race sunday.

I had it tuned by the local Guru first. Header/pipe 41030/9901. NR#6, 25% fuel, 1.0mm springs + alum 3shoe (stock mbx6 clutch)

Felt okayish on the track during practice, low-end pretty weak but engine still below the 1-gallon mark.

Engine collapses after 5mn -> reopen HSN a bit, becomes much more consistent.

going to 1.1mm springs -> pick up a bit of low-end grunt

and the grand finale: Local guru installs full 2057 exhaust while I was marshalling, just for kicks, without telling me: wow NOW I have a real engine, he only told me after the 3rd main (club racing - 3x5mn qual + 3x15mn mains).

Local guru's explanation: 41030 header curvature radius is way too narrow and screws up the acoustics. Next steps: try the 9901 with the "stock" 41021 header which is a crappy fit in the MBX6... well, one can't have it all I guess. One of the local track hotshots also run N21R + 41021 + 9901 and his mill is in the top decile of all local racers...

Any opinions on whether the header's curvature can really choke a mill like supposed?

Thanks

Paul