I have a jdm 4-1 header and had a 2.5 flange welded on the cat. Everything bolts up but the screws loosen every couple of days. I tried locking screws too and it only made it a couple of days more. My local muffler shop suggested an HKS flange that has play but that's hard to find and a bit pricey. Any suggestions?

 

Are you using the springs and locknuts that Honda normally puts in there? Without the springs, I can see how you would have problems, because with the engine movement, the bolts would tend to get twisted around, and could loosen up.

 

No I didn't...but I still have them. I ordered an O-ring to give the header and the flange a little play...I will use the stock bolts w/springs then...Thanks !