Basically it's 4-2-1 header mandrel bent config is 1-4, 3-2. Special part is from extractor it joins the flexible pineapple and the pineapple joins directly into 1 midbox, it actually comes as a single piece pineapple and mid box, then about 12 inches down second midbox, yes 2 midbox, both medium sized. After that is the muffler straight flow. Route is still the same as original piping. Diameter if i am not mistaken is same as stock or at least on mine. I know because there was an extra pipe that came with the set that wasn't used and when i compared it to my original pipe, it was an exact match. Did not bother to measure though.

If you are thinking of copying or making your own, don't bother, it's so bloody cheap now to buy a set and install. Don't know if they still have stock though.
Like i said above i had an extra pipe which i put end to end with my stock set and it matched exactly, hence my assumption. But of course i'm not saying you're wrong but that's what i did.

When are you getting it?

Can't tell you exactly coz i never follow the prices, when i bought mine it was 1200 full set on offer somemore, now is around 700 something full set.

Summary yes totally worth it. The driveability of the car has improved a lot with the torque band moved much lower having more pickup from 2k rpm onwards compared to 4k. There is no more switchover point at 4k rpm it's smooth transition through. Top speed i believe has been reduced but i never tested it and doesn't matter to me at all.

Previously my engine has the pinging problem at low speed due to the ECU being the first version, 3 days after installing the pinging stopped completely, i can now wide open throttle in 3rd gear at 40km/h and no ping at all which only means the ECU likes the setup very much. I was using Marco extractor with stock mid and muffler and it wasn't really nice because power was not smooth and the engine still pinged.

Anyways it's not only me who is using this system, i know a few other guys who have flogged their g2's to death searching for more power and all of them agree that r3 gives the best overall. They proved it both on dyno and on the track as well.

FC is about 250-300+ full city jam like sh1t and 400 something for highway/mixed driving.

cap ayam header also about same pricing but is not mandrel bent