TRD is supposed to be working on one but it isn't ready yet.
It might be sold under the TRD, Kaizuma, or L-tuned brand.
There are other companies (like Area 51) that have centrifugal blower kits already for the IS300.
It is hard to know (yet) how reliable they will be over many thousands of miles of use.
Also, emissions laws have to be dealt with.