Re: remap/induction upgrade vs fuel economy
i found that when i only had the induction and remap i was getting a slightly better mpg when i drove sensibly, however the car felt so much more responsive i rarely drove sensibly lol. as mr.orange has said, you should be looking at up to 15bhp gain from induction and remap.
one little tip tho, if your going to get a custom remap make sure your car is running perfectly first, ie, service it before it goes along for the remap. makes it much easier to get the most from it than if its running dirty oil, blocked filters etc.
as for using 98ron, never herd of that for jsut induction and remap, although i use nothing less myself my car runs very rough on standard 95ron stuff!