so you ordered an IWG 8374, ok. and i think you might be confusing the two. the IWG has one 42mm valve head/36mm port not two. the TS EWG model will require an uppipe that utilizes two EWGs as it's obviously divided.
and since you're IWG, i have the high-pressure canister you'll need that i'll sell to you cheaper than you'll get from full-race. i have no need for it now as the person that bought my 7064 wanted the medium canister and i am on order for the EWG 7670. it's already threaded further up the shaft to work with subaru fitment which saves some hassle. shoot me a PM if interested!