So looks like I'll be putting them 6" back. I don't think I want to cut that crossmember. Thanks guys.

 

could you just drill out the riviets that hold it in and slide it back a couple of inches redrill and bolt it in place should take an hour or so or cut out section and put an 7x7 steel jig weld it in and run exhaust pipe through it

 

all good ideas, I'll have to see when I get the kit. Any other suggestions are appreciated.

 

I like the stacks as close to the front of the bed as possible so when we did my single stack we cut a chunk out of the cross member... with the tool box in there will not be any weight up there. when we put dual 6's on a friends truck we took out part of the bed cross member and about half inch out of a frame cross member. no problems at all.