I'm rebuilding my T2 with 9.4 rotors and I plan to run around 12'ish PSI with an Rtek or some piggyback ECU (not an SAFC more like a sprint RE or e-manage).
My questions are, at these levels of boost, would an ECU like an Rtek or a platinum sprint RE be good enough to control ignition and do 3mm apex seals really help that much more? Do I have enough room to use 9.7 rotors and if I do, again, would it be a worthy investment to mill them to 3mm?

Also, whatever rotors I get, I need to swap out counterweights to match right??

 

yes on the counterweights.
there are plenty of peeps running rteks and the like with 9.4cr rotors, however i beleive they all use 93 octane, which i run 9.4's and a stock ecu at about 7-8 psi all day long with 93 octane, how ever with 87, it pings like crazy and WILL blow, did once already.

i'm an 87 octane freak so i'm going to get an rtek( hopefully The new version if they release it any time soon) and be tuning for 87 octane, i think you could get away with 9.7s pretty easy on 93, eventually i want to move to rx-8 10:1 rotors and a bnr stage 4, but i've got alotta of tuning practice on cheap rotors/housings/stock turbos before i attempt to try something expensive.


As for the 2mm vs 3mm.. most people would beleive there's a huge safty margin by going 3mm.. but alot has come about that you can still break them. The 2mm are CHEAPER, seal better and aren't going to break at the first signs of ping.. like most people would like you to beleive, i've broken apex seals twice.. but both times was near 6k rpm in 4th or 5th gear, a few pings in 2nd or 3rd never blew the motor( not saying it coudln't, it just didn't) and those few pings should be enough for you to know you need to change your tuning. i was FOOLISH i couldn't stop myself.

 

Just noticed how messed the title is...

Yeah, highest octane I have access to here is 91, plan on getting an AI kit too some time in the hopefully near future so hopefully that will add some safety.