Maybe people who have modified the intake or exhaust on their s could help me here!

(science bit )
If you improve the intake and exhaust the engine finds it easier to bring in fresh air and push out the exhaust, leaving more power available, therefore increasing the bhp. This (I think) is achieved through burning no more fuel? But I have always been under the impression that increasing horsepower would lead to a decrease in mpg.
So what difference does improving the exhaust and intake have on your fuel consumption?

(and if my science bit is wrong can anybody correct me!)

Not sure about the exhaust side effects on consumption but on the intake side it will increase fuel consumtion as if it gets more air it will automatically be fed more fuel so as to maintain the optimum fuel/air mixture. Hence also the performance gains.

So getting something like an induction kit will increase the fuel comsumption?

I'd second how Nick has put it, an induction kit will allow more/denser air into the engine, the ECU will then add more fuel so the mix is right and that's where your (albeit small) power gain will come from. So yes, if you fit an induction kit then you will see an increase in fuel consumption. An exhaust shouldn't have any immediate effect on fuel consumption though.

But more BHP less need to floor it all the time,you may work lower down the rev range and actually save some fuel?

Fair comment Peter, but then I think with more bhp, coupled with the noise of a replacement induction kit and exhaust, I'd be inclined to drive the car harder, more of the time, thus using even more fuel!

Parksey i,m 100%behind you on that mate,give me more BHP and I,ll use every last hair on that horse.I try after every fill up I say to myself at little less Fitipaldi and a little more Mr Molehusband (remember him?).No chance theres a vortex under the accelerator peddle that just sucks my foot to the floor.

Yeah i'd love to hear of anyone who has done the modifications and what kind of mpg they are getting now?

Reginald Molehusband... Wasn't he from some sort of TV ad. Can't remember what for though.

Reginald Molehusband was from a public information film about parking. Theres an (audio-only I'm afraid) link here.

http://tv.cream.org/specialassignments/themes/ads/regmole.mp3

The name's familiar but I don't really remember it. Think it must have been a little before my time! (sorry Peter...)

I had heard the name before but coudn't remember much about it. It must be before my time as well, as according to the site where I found that clip Reg was driving an Austin 1100 in that film!

I feel really ,really ancient now.But I was a kid at the time.He existed in the time before the roads were jam packed,cars were just becoming popular/affordable and drivers did,t know how ,(probably because there was no need )to reverse into a parking space.If you watched it today you,d pee yourself laughing.And yes it was an Austin 1100 top car for the times.
Bye just off to kick start my zimmer.