17/18 year olds tearing around the country side in "hot" hatches.... Nice knowing you Adam.
Whilst we all feel invincible behind the wheel, you and your mates would do well to spend some money on performance driver training. That way you will reduce the likelihood of going through a hedge backwards the day you discover ease off oversteer. You may even find that you reduce your insurance too.
I thought I was awesome behind the wheel until I did a training day on an airfield with a professional racing driver - I was very average in reality and made all the mistakes Mr Average makes.... This was after 12 years on the road, 100's of 1000's of miles, mostly in high performance cars.
A few hundred quid on driver training will make you quicker than a few extra BHP and safer than a set of big brakes.
Just my 2p worth.