Indeed that’s what I use.A single 18 BR cabinet can not keep up with the PM60/90. A tapped horn like the TH118 has much more output (but is twice the size/weight). 4 tapped horns with the 18sw115 would be a perfect fit and will put a smile on your face :-D
I’m using one TH118 with 18sw115 per side (limited by my transport) with PM90 and I feel I could use some more sub (mostly on outdoor events). I think the PM90/TH118 combo is about the most powerful, compact sub-top set that you can build at the moment and that can be handled by one person.