CKit

The definitive solution is to puchase and transplant an AP2 rear subframe. The toe attachment points are different.

Bumpsteer kits work, but often are "race parts" that need routine replacement.

But like Jim said, there's probably another factor at work here if you're finding the drive too twitchy.

punchdrunk

My AP1 has MY04+ 17's with 245/40/17 and 215/45/1 tyres. I've also had the alignment done - it was way out beforehand and have just fitted a front lower brace. The brace made a huge difference and there's a vid on youtube comparing the differences between AP1/AP2 - the AP1 was 0.5 second quick around the track on the larger wheels.

The anti bumpsteer kits are meant to eliminate the RWS effect but I'd suggest more seat time to get to know the car. When you get used to it you'll find it handles just as well as the miata, more like a go kart.

ZDan

Forget about 245/45-16, the best street tires are only going to be available in 225/50-16.

I hear you on the funky AP1 handling, it's bizarre that Honda committed the same exact "rear wheels toe in with bump" error that has been made in the past. Stupid, and actually makes the car more prone to bite the uninitiated.

You do get used to it, though.

My personal approach is to avoid replacing primary structural components with aftermarket parts, so I don't think I'll be getting a bump-steer-kit for my AP1. If you are at all considering stiffer aftermarket springs/dampers, that would reduce the effect somewhat (less jounce/rebound motion, less toe change).