The boost in torque lower down the range should make it feel quick.

Modern N/A petrol engines do not respond well to re-mapping like a turbo does. To get more power you need to burn more petrol in more air, in a N/A re-map all they can do is change to ignition timing and injection settings to the absolute optimum but the gains are small, 15% is their claim, reality may be different, read the small print.

But modern engines do have a lot more unrelased power available simply because they are strangled by emission kit, noise regs and packaging issues. With the correct parst there is plenty of gain to be made.

Take the 2 litre Focus Zetec in the Caterham. Ford claimed 134 PS for this engine (132 bhp). I removed the fuel system and replaced it with a Jenvey twin 45mm throttle body set up on a special manifold (looks like a pair of Webers) fitted with Weber Marelli Pico injectors (as used on the V twin Ducatti superbikes) breathing through a pair of K & N cotton gauze filters. The fuel is fed using a high pressure Walbro pump (same as used on mapped Scoobys), the HP pump being fed by a low pressure Facet red top pump and swirl pot. The injection and ignition is looked after by an MBE mapable ECU ( as used by several low volume manufacturers) and a custom engine loom. The Ford exhaust manifold was junked and replaced by a 4 into 1 tubular set up into a 2 1/4 " silencer.

This set up allows plenty of fuel in, plenty of air in and a free flowing exit for the waste gasses.

Not cheap by any means but I was able to sell off many of the surplus parts from the Focus engine plus parts my previous twin Weber 45 set up with Weber Marelli ignition. Net cost was in the region of £1500.

The result is 175 bhp, 41 bhp more than standard, about 31%. There would be more available if time was spent optimising the cam and ignition timing on the dyno but the cost per bhp would become daft at this point.

But its only relevant to older cars where the emission rules do not demand all the OEM kit be fitted to the car. My Caterham is classed as prev 1974 so basically there are no rules.

But having said that, this engine, whilst being way more powerful than an old x-flow on carbs also uses way less fuel thus logic says its a lot cleaner.

If work needs doing go ahead but have a good drive in a converted car and read the small print first.