If I have the laser cut subframe connectors would I still need the underfloor brackets - I am thinking of installing the 6 way brackets for more comfortable driving, thank you
-Steve

I have a 70 Challenger convertible that has the 6 way seat. It doesn’t have the under floor pan brackets, they must have got lost when the previous owner restored it. Getting the repros has been on my list of things to do but I never have got to it. In the meantime I’ve owned the car over 20 years and put close to 10,000 miles on it, I weigh over 200# and I’ve never seen any evidence the floor or mounting has been damaged not having them. And I had the interior and carpet pulled out a few years ago to replace the carpet so did get to look at that area closely then.
You might want to see if you can find someone with a hardtop with 6 way seats and try sitting in it before you add the option. I’ve heard a number of E body owners complaining about it, as the mechanism raises the seat height and affects head room. I’m tall and I’ve never had a problem with mine, but 98% of the time when I drive my car the top is down, so headroom is never a factor! I think even top up, convertibles have more head room due to no headliner etc, as I’ve never felt uncomfortable the rare times I drive further than moving the car out of the garage top up either.

The only thing I know about the 6 way seat brackets is they move your head closer to the headliner. I had to remove the ones in my 70 Charger because when I went racing the helmet would be all up in the headliner and I'd have to slouch down...I'm only 6'1".

Thanks for answering my post, my question really was do I need to spend the extra 140bucks for brackets if I already have welded in subframe connectors that add strength to the floor, thanks

are you asking if the 6 way bracket reinforces the subframe?

The only thing the 6 way seat reinforcing brackets do is help distribute the load over more floor area for the extra weight of the 6 way seat mechanism (maybe), and reinforce and distribute the load for the floor mounting for the variety of bending moments created by the seat being higher and being able to be adjusted to different angles with the six way seat (more likely). If you aren't installing a six way seat, they aren't used or something that provides much benefit to the body integrity.