This FAQ has been created to explain what the stages of tuning a mini engine are, giving you expected power increases, how they achieve these increase, and any other advantages (or disadvantages) and implications of them.

NB. Where ever possible I have tried to use the same names as used in a Haynes manual, so if you are unsure as to what or where anything is, it should be simple to find it in a Haynes manual.

Standard Parts
Before you do any sort of modifications to your engine you want to make sure the standard components are tip top. Theres no point fitting that brand spanking new Stage 3 cylinder head if your ignition system is old and providing a weak spark. Standard service parts are:

Oil filler cap
Radiator pressure cap
Air Filter
Fan belt
HT leads
Distributor cap
Spark Plugs
Oil and Oil Filter
Rotor arm
Points

If any of these parts are worn they can impair the performance and efficiency of your engine. In addition, a session on a mini friendly rolling road can do wonders, and advisable with a change of air filter. Also, with all of these parts it is perfectly acceptable to replace them with completely standard components, there is usually little or no benefit to be had with so called 'performance' versions, especially when buying spark plugs!

Stage 1 kits
Stage 1 kits have now been on the market almost as long as minis have been on the road. Due to this timespan certain companies have been able to develop kits so that they are now very efficient and are able provide a good 'bang for your buck' value.

A stage 1 kit can differ from company to company, but generally they consist of inlet manifold, exhaust manifold, exhaust system, air filter, carburettor needle (where applicable), gaskets and clamps.

Most companies boast a 15-20% increase on your engines power output. The way they achieve this through better gas flow into, and out of, the engine. The more air and fuel mixture you can get into the engine, the bigger the explosion will be that ultimately drives the wheels. With this however more exhaust fumes are created and therefore the need for an exhaust system that is capable of removing these fumes.

One thing you must budget for when buying a stage 1 kit is the cost of a rolling road session. This is an absolute must if you wish to get your mini running at its best. Otherwise the £150+ you've just spent on performance parts has gone down the drain.

Apart from increasing the power output of your engine, there has been reports of increased economy. This could be purely because the car is now set up to run at its most efficient and so is no longer feeding excess fuel through the engine.

One disadvantage of fitting a stage 1 kit can be insurance issues. It seems it depends very much on which company you are with and can even be down to your age. Some companies won't increase your premium one bit, others won't allow any modification of your engine at all. With all cases its best to talk to your insurance company BEFORE fitting a stage 1 kit to find out how it will affect your policy. Another disadvantage is that because the car is now more 'livelier' and quicker, your tempted to put your foot down more than you did, therefore actually decreasing fuel economy.

Extra reading: Insurance implications, places to buy.

Places to buy: MiniSpares - Small bore cylinder heads, large bore cylinder heads, large bore (with HIF carb), SPi/MPi.