Thanks guys, I think Ill just go with an SAFC or similar because I can switch between tunes and tune myself with a wideband, at least for a fuel economy tune. But anyway, we're getting off topic, as my original question asks, whats sort of difference does the basic bolt on mods make in a 25? Like I said, in an SR20 they apparently make quite a difference, just wondering if the same applies to an RB25 and if experienced folks on here could throw out a low rpm and high rpm power difference estimate?