Had one on my 3L. Was awesome. Just don't buy the eBay ones, they leak and the finish is really shit.
You can get them for about $350 from an Autobarn store, and they come with all bolts, hose fittings etc. even have a little section where you can put your greddy sticker, so you can tell the poor kid that you sell your car to that it has a blow off valve, and greddy intake manifold.
The larger TBs bolt straight on too. The standard one needs an $80 adapter.