Would suggest you call Mark Jorgensen , Woodhouse Motorsports Division Mgr. , on Tuesday as he and his team have installed over 300 Paxton’s and he can give you plenty of advice on what you should or should not do, etc.
There is no need for the overflow tank, the systems do not run how enough to generate considerable pressure. You are likely still working out very small air bubbles in the system, and slowly expanding hoses and tank as the system warms up.
The radium can I cannot comment on, as we dont generally use them.
So I recently put one on my 04 and I have a few questions. First, should the intercooler cap be vented somehow or have a overflow tank. If no, then how full should the intercooler be filled? Right now Ive been filling it all the way, with a unvented cap. I seems to have to add a little after each trip and I dont see it leaking anywhere.
Second, fir thise with a Radium Engineering catch can, where are you mounting it? I cant seem to find a good location/fit anywhere.