You have scheduled maintenance coming your way at a little over 100,000 miles, open the owners manual. Timing belt kit, plugs, etc. Just get the service up to date and replace worn out parts, spend on quality oem parts or better when possible. A stage 2 setup is fun and fuel efficient, properly done it is rock solid reliable. I have an 05 Saabarex on stage 2 with 147,000 miles, 142,000 on stage 2 level performance. Preventive maintenance and not abusing your car is the key to reliability.