[Penguinracer]

I gotta say it, but after spending a lot of money developing an "S" there does come a point where you have to say "enough's enough" & admit the limitations of the platform & surrender to the "P" word - "Porsche!"
When I say Porsche I mean any Porsche other than the Boxster/Cayman/Cayenne.
A highly modded Mini has the benefit of being something of a "Q" car which is massively underestimated at the track. But there does come a point when you have to decide if may be you wouldn't be better leaving the Mini alone & trading into a 964 or a 993.

I suppose my point is that to make a Mini fly reliably & for year after year you really need to spend considerable money on the diff, ,wheels, tyres,suspension & brakes on top of any engine mods.

With a well cared for older Porsche - the quality & over-engineering just shines through - straight out of the box!
My brother & I found the lure of the 250 bhp 944 turbo proved too strong to resist & we bought one each. Their tuning potential is enormous & no more costly than modding a Mini to a top spec.
I just thought I'd throw a curve ball in there because a clean 911 is very good value now & their engineering quality is renowned. Yes maintenance costs will be considerably higher but depreciation should be lower. Just another perspective before you get too carried away!