Shock confusion

[monkeyman_300]

Hi. This is not my first time on here, just had to re register after log in problems.

I am having a bit of trouble making the right choice. I have done ample work on my L1 so far: re-built/ re-sealed forks, new discs, cbr900 rry calipers (rebuilt etc.), double bubble screen, delkovich downpipes with remus end can etc. etc. but can't decide on the right shock. I'm looking to sort the handling out for fast road/ track riding. The bike in going on track in about a month for my first track day and I don't want to use the standard shock.

I have the option of a regassed/ serviced whitepower for £240, a good condition sp for £70 or gsxr or something else of a different bike (zx6r etc.). I'm a student so as much I would like the Whitepower and know how well regarded they are £240 is a bit steep right now. Can anyone tell me if the sp shocks or gsxrs etc. are any good for what I want. I want to get a noticeable improvement without breaking the bank. Someone tell me what is the best option. If it helps I am about 86kg with all my gear on.

Thanks for any help in advance.

p.s. I know there are loads of threads on shock but filtering through them is not answering my queries.