been racing a tt01 one-design class for a while now and I always used to have both diffs under a very light coat of ptfe. Results have been very good on medium grip asfalt. But I have also raced a rally car with a one-way front diff and I have a ta-05 where I am appreciating tight front diff (spool is on order) so I have a race coming up in tt01 and I have just packed the front gear diff with thick black grease. I'd actually like to locki it up completely but I will first go with black grease and see how it goes. I know m-05 guys that put plastic bits in the gear diff to lock it up so I may go down that path.