Pros and cons please as ive heard it also gives slightly more clearance also as well as more lows.
It gives slightly more clearance.
I thought you were going to make your car handle properly as this year's project?
A quick Google threw up this list, something to think about (though not necessarily all gospel)
1) MOT fail as the spring will unseat when not under load.
2) They're designed to run with the helper springs and the spring rate of the main spring is set accordingly. Removing them will screw up the spring rate and handling made even worse than it is already on maximum drop.
3) Strong possibility you'll be reducing the damper travel to the point of it bottoming out, which will kill the dampers pretty quickly unless the roads round your way are as smooth as glass.
4) Your wishbones will be pointing upwards ruining your roll centre and causing bags of bump steer.
If you really have to go that low without using air ride you should really move the suspension mounting points in the car upwards to keep some of the travel.
I've lost the helpers on mine to clear the 245s, but the car isn't slammed. The height is set so that the spring doesn't move though. There has been no difference in handling as well.
Buy shorter springs?