When the kits say that they're for off road use only, it just means that they're not carb/emissions legal. So if you don't have emissions tests in your state, then any kit will work. The only problem I see with the TSI kit, it that it comes with a T25. That tubo will be good for what you want (it spools fast too), but if you're going to end up building you engine later on and turning up the boost then you'd be better off with something else. Me personally, I'd go with the Drag kit (I also don't have to deal with emissions though). I've seen some real nice gains from that kit. There's also a dealer for them that is selling the complete kit for $2,600 shipped over at Honda-tech. So if you're a member of that site, you might want to look into that. Here's a link:
http://www.honda-tech.com/zerothread?id=981195 and here's Drag's official web site
http://www.dragturbokits.com.