What a pain inthe butt.
Have yoiu thought about either 1) getting a well sorted out GT-1 car (and keeping the motor stock) or 2) getting a Comp Coupe?
What's nicest about either of these 2 options - is that you spend your time driving as opposed to messing around in the pits and at some vendors area trying to get things fixed. The stock motors are way understressed, you can compete on a level playing field within Viper Days and you'll have more fun!
I can only imagine the $$$$ that's gone out and it rewards you by what appears to be less and less driving / racing time. I'd be ready to call it quits - your perseverence is extraordinary.
“Anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your knowledge.'”
― Isaac Asimov