Apologies for the slight thread drift, but this is something I've never understood.
If you spent your money on making yourself a better driver, then you'd be quicker in every single car you ever drive in the future. If you spend your money on going quicker in a straight line in your current car, then you're back to square one when you move on. Improving ourselves as drivers is the one on-going challenge that every single driver ever can do, regardless of budget. Even simple things like learning how how to position your car correctly at corners, or learning to heel & toe, these things will make just as much of a difference driving in town as they will on the open roads.
You can be as good a driver as you want to be, and it's a transferable skill. Without doubt, if you spent £1000 on driver training you'd be quicker than if you spent £1000 on an exhaust and remap.