custom exhaust: how to collect the RB header into one pipe for single N1 exhaust????
 

what do i need to do this, ill be using the RB header with the aux port tube since ill be running no cat. thanks.

I'm assuming your using the road race header. Most any muffler shop will be able to fabricate something of a collector pipe. Most will have the supplies and equipment to do it. But you want one the merges at a very shallow angle not the the letter "Y". Finding the right muffler shop can be a challenge.

Why don't you just buy the RB collected header? Then all you have to do is get the RB presilencer and the N1 should bolt right up.