Greg, go a good pod filter for now but in dusty or extreme wet conditions you'd be best served with a shroud or box of some type to keep it half clean. Not only that, these motors seem to respond better drawing from still air. I found the ER gear ratios pretty close to right excepting they too suffer the same fate as the TM early RM in having only 5 cogs to play with. They simply run out of puff a little too soon. With a fresh top end if your TS doesn't pull the front wheel off the ground 1st thru 3rd under hard acceleration on bitumen in stock trim then she's a little down on power. I've had a few of these reed valved models and they all went exceptionally well and quite snappy after rebuilds.
CG, that pipe does look like centre port alright but still the ad is very misleading on the models it suits. I'd be going a down pipe on an early model and one could seriously think of doing the same on an ER and thus retaining the sidecovers
I slipped Pokey a pair of TM125 gear clusters but still the problem exists in the early model of the pressed gear spinning on the imput shaft when too much HP is applied. Have heard very little success in fixing this issue, even after pinning and welding.
I like the idea of the TM185, being a small bloke I find even the TM250 feels too heavy and I'd surely get a 185 around just as quick (slow) if not quicker (a bit faster than slow) and not need an oxygen bottle after the fact