Depending on how tight those tips fit on the cans, only one bolt may really necessary to hold them on.
When I put on my 18" Air Flow truck stacks, I took a long time measuring, dimpling and drilling them to line up with the 3 bolt holes on the cans. Then, they fit so tight, I had to put a soft piece of pine over the ends and hammer them on with a mallet. I used all three screws since I had taken the time to line them up and drill them, but those things would have never come off (or even have got crooked) with one bolt.
Assuming you are not moto crossing your Valk.
I don't remember how tight the OE tips fit.
Jess when I put stacks on my standard I had to put a pillow on the garage floor and pile drive them on. Used no bolts and would Dare say they will ever move without using a torch or cutoff wheel

I put full “36 length stacks on though not”18.