honestly the newer ISR stuff appears to be much higher quality (manifolds at least, I still wouldn't use their arms)
I got one for the KA-t vert I raffled off, to replace a cracked and beaten old one, and the ISR one was very beefy, perfect fit, welds all look consistent and have good penetration anywhere I can see inside.
https://www.enjukuracing.com/product...RoCYcUQAvD_BwE
a while back, I ended up with one of the Gent5 manifolds FRSport had for sale. Ended up selling it to Jay from Realize and it sounds great on his car. So far zero issues with it either. Kinda wish i'd kept it (still, 0/10 do NOT recommend anyone try to order ANYTHING from FRSport)
https://frsport.com/gent5-g1101-exha...-s13-14-15-rwd
also, sch40 is only 3.556mm thickness at 42mm OD, the gent5 is 2.0mm thickness.
Have you had experience with runners breaking in the past?