I had an RX-8 for a while, the idiot owner before me blew an engine and also f'ed up three synchros. When I got the car (with the second engine) there was about 2 quarts of extremely dirty oil.
Now, tell me about the rotary engine being unreliable.
The engine never had an issue while I drove it for about a month. Mazda now offers 100,000 miles or eight years for all RX-8.
As for power, just add in a single turbo with ECU upgrade. You can make 350 wHP EASY and no internal reworks require because the rotary just likes forced injection. Just make sure you don't get any detonation from wrong A/F ratio.