Hi..LP is around 450...wouldnt think of putting one on a Race Cocker, as the recharge rate of your regs will have to be insanely fast. If they cant keep up, you will get major shootdown at High ROF.
Stick to an HP, or, instead of getting another preset, get a Nitroduck Extreme reg. Its about half an inch longer than a preset, looks the same, but is adjustable, and very very good. £75 from Pheonix.
Not sure what Race's run into them, but most likely around 325 from the Inline reg...so run approximatley 550/600 from your main reg.