Sad to hear that he's dropping the ball.
SLP has been out of our market for a while now, like TOG, so anything out there is legacy parts from 10+ years ago.
I can tell there's slight changes in the SD's from my original SLO clones from 15yrs back, but there's definitely a gain to be had. I was tasked with dynoing the difference between manifolds and the headers.
LINK to chart
They better me the same ~25whp as SLP used to claim possible. (XP, 105", Gen3, 3.3") That made sense when the pipe diameters and layout were identical, and SD's are essentially the same, barring minor fit issues due to quality control.
ZZP has really the only new option outside eBay offerings, but it's up to what someone wants to pay, when they're in stock.
