I went with an RK-TEK head as well on my 18 300. The bike runs much better with it now. Before it was a little finicky with jetting and had some slight detonation here and there. The bike sounds different now. Super crisp.
I don't have the CDI remap done yet but plan to get it done. It feels...
Saw someone racing an ALTA at the NEPG Enduro. At the gas stop he had to pull a fresh ALTA out of the van to continue on with the race..............which isn't legal. Electric will need to have a FAST way to swap batteries or be able to go for 4-5hrs at a time. Neither is possible right now.
I didn't find much info at the time but did use YZ250X front springs in my 18 GG. They were the same. If you contact Budd Matto at Matto cycles he has details and springs I'm sure.
Another resource would be JDP Suspension in OH. They do the NEPG Factory GG Suspension and have a ton of R&D on...
I had a 17 KTM250XC. Hated the AER forks. Spent $1300 and installed Dal Soggio Sphere cartridges. Also installed a different linkage arm/ratio and had a shop redo the shock to match. (another $850 for all the parts and changes and shipping). At that point the bike was really good. The new 18 GG...
What bikes come stock with one? I think you will be in that boat with whatever bike you choose. I've not seen an end cap for the GG FMF silencer out there yet, just the whole 2.1 like you have seen.