yeah when I heard disco potatoe I was like WTF? but the best bang for buck is an S15 T28 even if you can't get the BB version the bush bearing version is almost as good. There is a huge difference in the top end (but thats becuase of the bigger exhaust and compressor a/r and bigger trims) the stock T25 runs out of puff to early and you can feel it.

The only mods I had to do to fit it to a stock manifold was elongate the top dump pipe holes and slightly rotate the housings.

Damo