E36 ITBs fit with a little modification and an aftermarket ECU, a little bit cheaper than the DBillas ones

The port spacing and profile are near identical and the lower mounting holes line up pwerfectly, the rest requires a little bit of custom work and either some trumpets (velocity stacks) and/or a plenum manufacturing. They sound great, that's for sure but with TimS getting 200bhp on a stock inlet with ported TB you have to wonder how worth it ITBs really are.
I find that my car pulls hard to 7k on stock inlet with chip, regrind cams and exhaust, the last few 00 RPM over 7k might slow a little but that's not a suprise.