is it worth having this done to a classic impreza and if yes, why?

Yes...

It reduces (almost dials out) the inherrent understeer.

It will increase stability under heavy braking and generally tighten the front end of your car. You will have to have your geometry settings changed accordingly.

Imagine that under heavy braking the nose of your car tips and effectively the wheels and tyres splay outwards like so / \... ok?

This reduces the amount of actual tyre/tread pattern that is in contact with the road at any time thus reducing braking effectiveness and therefore increasing the tendancy to understeer.

The bumsteer mod shortens shims and holds the wheels like so .... l l under braking, meaning more stablity. This also reduces the amount of brake flex that happens so all in all it's a good thing :D

The downside is that tyres may wear a bit quicker :(

Phew.... ;)

thanks mate i'm having the geometry done at the same time at powerstation but i just wanted to check i was doing the right thing.

Dave

Take it easy for a few days after getting this done as your car may appear to be a bit 'rear end happy', cos your front will be gripping so well.. It may take a bit of getting used to so watch it on the limit:D

ok thanks mate, tail happy will actually suit me so hopefully the car will be more like that!!!