[turbonutter]

I would also guess that the pre rad is the problem..

Just as a quick test, as I have a spare EWP115, I connected them in series & that increased the flow from 25 to 36L/min. I have 25mm pipes & the tanks on the pre rad are only 25mm wide, so 32mm pipes wont fit, I will look to see if there is a way to improve the flow, but it wont be for a few months, as I will be working away in china... The Space around the pre-rad is also very tight, so not much option to change the pipes. I guess the easiest would be to use a better pump....... but not sure which pumps are better....