SPT940;26983 wroteI'm meeting with a guy from Hallam Performance who is supposed to be a genius extractor maker. I'm getting him to mod the ones I recently picked up (probably hurricane). Need a lot of port matching and the welds cleaned up. Changing the collector to a, two into one @ 2.5" pre cat with a flange fitting. Having then ceramic coated afterwards. Got a 2.5" hi flo magnaflo cat. The rest of exhaust will be 2.25" reduced from 2.5" after the cat.
I had mine port matched as much as possible, but the size of the primaries is a restriction. There's no need to replace the 2-1 collector, you can simply cut off the piece where it tapers down to a 2" outlet, and weld on a 2.5" pipe.
Doing these things will only help so much though, as it's still far from an ideal design.
I'd like to see something like these, but suitable for a RHD 240: