The car you have is the 2010 RMD ITA Championship car. It is a proven winner in Colorado sense 2008 when it moved here. It was within 2 tenths of the PMP track record in the ice conditions of the 2009 enduro and it is capable of braking the current track record at HPR (I would be happy to break the record for you in our first race there). It is a proven commodity the way it sits. If you change the setup you won’t know if it is the car or driver that can’t go any faster. I would suggest you leave it alone until you are running the times you know the car can run. Ones you get to this level by all means make changes to suit your needs.

Currently, the only issue with reliability was due to fuel peculation when it was running 85 octane pump gas in 100 degree weather in our high altitude. High octane has cured that. The thermostat is already removed and the bypass plugged. Adding an air dam will also help keep it cooler with our low air density.

Heavier rear spring will make the car more prone to over steer. It is already leaning towards over steer as it is. The only suspension change I would make is a try-link. Even that would change the proven package you have.

Your original post said you want to create a reliable/stable car for learning on a budget. That is what you currently have. If you change it you may move away from this combo and not even know it.