They're decent. About the same as an RT615 in terms of grip, maybe slightly less but they're not as loud and they do very well in the rain. Steering is crisp and responsive. Problem is they don't take heat as well as the newer tires so they can grease over if you're not paying attention to them. They seem to run a really soft compound.

I'd say do it If you can get the second pair for cheap. Its better than K104's IMO but they're not going to last that forever, but thats what the E30 is for anyways.

I might end up ditching all 4 of my NT05's next month instead of just two, so your more than welcome to try the front tires out. They'll still have more than enough life on them to be decent at 4-5 auto-x events. The grip from those things is insane.