MX5 on Carbs

[PorkChop]

The stock MX5 inlet manifold is pretty good for an OEM item (as is the exhaust manifold come to think of it).

You wouldn't get much change from £500-1000 depending on how much you can do yourself to fit ITBs. So you're getting into the sort of budget that you could build a low pressure FI MX5 engine.

Another option is to look at Blink Motorsport's recently offered cylinder head & cam package over on MX5Nutz. £1250 + VAT for a worked and refurb'd cylinder head, hotter cams, wideband lambda and a PNP Megasquirt.