The choices for off the shelf headers on a RX-7 swap are limited. After a period of contemplation, I settled on a set of Spoolin Performance headers for their incorporation of merge collectors. These headers seemed to be of good quality and construction versus the competition. The community consensus for fitment appears to be straightforward as well, so I’m hoping it will be the same for me.
Unfortunately, Spoolin was out of stock on their headers and I actually picked up their last 1-3/4″ headers at the time. The slightly larger 1-7/8″ headers were sold out. However, my research suggests that the noticeable difference between the 2 sizes should be minimal performance wise – depending on the setup. 1-7/8″ is supposed to generate better peak power and best suited for forced induction or larger displacements (400+ CI). 1-3/4″ should deliver the power more in the midrange, which compliments street driving well. Since my LS3 is stock and I have no realistic plans of drastically changing that fact in the future, I have no qualms of settling with the 1-3/4″ version. I’m hoping the smaller runners will also aid in body clearance, since every millimeter will count.
Here’s a shot of the inside of one of the merge collectors. I’m sure the actual benefits of a merge versus a stamped collector are not relatively drastic, the former is still more efficient because it allows the pipes to scavenge off each other, thus creating more vacuum.
To keep things fresh, I picked up a pair of GM steel header gaskets and a set of 12 point ARP bolts.