Well got my mg66 back from Rex (RW Modding) the other day and ran it today for the first time. Ran it around slow for 3 tanks only because it still had a good bit of mech pinch. Then started to lean it out. The Rex magic started to come to life after 6 complete tanks still just a tad rich temp 245 good smoke it was HOOKED UP pulling front wheels about 1" at the start of the straightaways.
13min run time with more in the bank.
I'll tell you what i am super happy. Running mbx6t 13t pinion 44t spur and plenty of bottom end. Novarossi ceramic bearings front and rear.

Thank You Rex
And Thanks to Bigmatt for the referral.

I also turned down some parts and replaced some.
Rotating Mass
Before After
Conical Diff Gear X2 44g 34g
Front Rear Outdrives X4 36g 24g
Center Diff Outdrives X2 20g 14g
Steel To Alum Axel Shaft X4 36g 16g
Drive Shaft Joint Cup Alum X2 20g 6g
Plastic Spur Gear 44t 30g 12g
7075 Alum Screws Diff & Spur X12 6g 2g
Total Grams 192g 108g
Saved Grams 84g
Saved Oz 3oz