Because that’s the trendy thing right now. I’ve typed this many times, but if you ask a cam grinder if they are adding exhaust duration or reducing intake duration you’ll never get an answer.
The only time I ever run a split is if I’m running alcohol (and at that I only had a 4 degree split) or if I’m stuck with a shitty exhaust.
IMO if the headers work, why add exhaust duration? IMO all that does is kill power right in the curve where you don’t want it to. Coming off the transbrake, in the gear changes or of street driving, right in the fat part of the curve.
I just don’t see a need for it.