I find with my GFB bleeder I get 1 psi more all round on a really cold night compared to a 30 degree day. It spikes a lil more, spiking from 12-->15psi sometimes on a 5 - 10 degree night, but its low in the revrange and lasts only 1/2 a second or so, so i dont mind. It doesnt worry me too much cos there is no such thing as a spike free bleeder. But i still want an EBC to keep things constant all the time.. No cash atm tho =(