I used Marine Grade JB Weld and put some inserts into my tray on my X2 last summer. I have rode probably 10-15 times with the straps and they are holding up fine.
I used the Jet Lyne old style inserts with the coarse thread on the outside and M6-1.00 on the inside. However I only put one insert into the tray. I felt that if you put two inserts side by side like the Dakines can have that there would be too much fiberglass drilled out for support. So far one insert works fine.
I will recommend this... I drilled my hole. Then I took my dremel and hogged out the foam as much as possible underneath the tray inside the drilled hole. That way I had room for more of the JB Weld. I was hoping for a "JB Weld" nut to form underneath the tray for extra holding power.
Also When I did mine, I had to use a bolt with a nut tightened against the insert to drive them into the tray. Well if you use the Blowsion ones, they have a place for an allen wrench. I would use my method though. The problem I had was JB Welded oozed up into the center of my insert after I took the bolt out. Granted it may not cure fully without exposure to air, I guess it depends on your epoxy. I would have left the bolts in the insert for a day had I known the JB Weld would ooze out. I had to clean the ooze out before it hardened. After I was done, I ran a tap down inside the insert to clean the rest out of teh JB weld from the center of the insert.
To get teh JB weld into the hole, I just used a sandwhich bag and cut the corner off of it. Then I piped in teh JB Weld liek a cake decorator. However once it sealed the hole off some, it didn't just flow right in. I had to use a nail and work it around inside the hole.
BUT! If I had it to do all over again... I would use acorn nuts! No sense in drilling holes into your tray and risking water logged foam. Even though must hulls will get water logged foam anyways...
