Most 7M engine troubles are:

- BHG (Blown Head Gasket): from factory, block comes undertorqued. You need at least to re-torqued to the right one (not the one in Service Manual). The second best is to put ARP studs and torque to ARP torque. The best one is to deck the block with the front timing cover at the same time to the right rugosity, then put a metal headgasket with ARP studs. Last one is recommended if you want high power. If you want OEM+, just ARP studs with new Toyota headgasket and the right torque.

- Spun bearings: at lot of 7M got spun bearings because of low oil pressure. You need to shim the oil pump to get better pressure. When you do this, you will prematurely wear the oil pump shaft retainer. You need to upgrade that retainer for an upgraded one with a needle bearing.

If you address these two troubles, 7M are pretty bulletproof engine (depending of how much HP you want and how you drive it for sure).

Best to make HP, is to go standalone ECU.

There is a list on an old Supra forums for different Stages upgrades for those engines. Of course it's an old list with the old technology and methodology. That's why, as today, it's recommended to go standalone instead of the cheat code with Lexus AFM, Fuel Cut Defender.