TWM, TODA, and Jenvy all make ITB's. However your best bet is to make your own off of a set of GSX-R 750/1000 ITB's or a set of Honda 954 ITB's. You can pick them up on ebay for around $75-$150 and have them ported out to 48-50mm for about another $100. Then modify your IM to fit the ITB's. Do eome research and you should find step by step instructions on how to do this.

What kind of car is this for?