I was looking at the B&H fitting water line kit, and it comes with a aluminum weld on bung, if i don't want to weld anything on my current radiator, how do you route the coolant line back to the system? Can I get one of those coolant hose port adapter thing from ebay? It has a port for water temperature sensor, maybe I can just use that to feed the coolant back?

If not, could you post some picture on how you did it? Thanks.

If you know what the thread size is for the radiator drain plug I can include an adapter so you can return it there.

I got one of this, can I use it as return?

nope. Just use what B&R has and don't look back. You're getting the rest of the kit from him, why dick around with parts you have no idea will work?

Cos I don't know what the thread pitch and size of the plug... emailed CXRacing, no reply yet. Can try calling them tomorrow. Plus, I already have that piece that I bought a while ago... and is just sitting there right now, wanna see if i can use it if i can.

take plug to hardware store.
find a nut for it.

B&R can definitely get you the right fitting. My rad drain plug was m10 x 1.0

Yea, well I just installed the rad last spring, and i need to drive my car this summer. I won't be asking the question if i can just take the plug out. I am buying all the parts now, so i can putting stuff in in the upcoming winter.

You have CXRacing rad? Would be helpful if it is.

unfortunately no. maybe just give them a call or email and ask? http://www.cxracing.com/service.aspx

Ok, called them twice, first time they said they would email me but didn't, anyway... finally got the size.
They said is 18 x 1.5... i hope this **** is accurate. they said they estimated it... (wtf)

There is no way that is accurate. Looks like you are going to need to measure for yourself.