A better check valve will help the braking problem for sure
Regarding tires, the 15/17 stagger is simply great. I also run the 245/225 setup. It's not a forgiving combo, as you'll be dialing out the understeer to essentially zero with the proper alignment. Beware!
I've been playing with Hankooks with C51 tread compound lately. Works extremely well and quite affordable...
I agree that the tire combo you mentioned doesn't seem like it would be the greatest for the car... Guess you could always detune the monster with a "small tire" map
Best,
Phil