Okay so I've found a few threads with similar concerns and none were ever answered... I just installed my HKS downpipe a week ago. It retains the stock donut gasket and stock spring bolts at the O2 housing. I tightened up the spring bolts until they bottomed out and wouldn't go any further. I was concerned I might have a leak during the past week, so I decided to take the dp off the O2 housing and re-mount it. The gasket is in prime condition so I'm sure it's doing it's job. My questions are: How tight am I supposed to tighten those spring bolts? Should I go all the way or back them off a little. Anyone know the stock torque specs? I backed them off this time, and I think my car got louder. It could just be my imagination though. I checked for leaks the best I could, but I'm not sure exactly how to check the O2 flange for them. I can't really get my hand up there to feel and I got burned when I tried. Any tips would be appreciated.

 

I want to know as well.

Note to self: Do all minor work myself! Even reputable companies can mess stuff up and not tell u.

 

Service manual says 37 ft lbs for those bolts. They shouldn't be bottomed out. That would defeat the purpose of the spring bolts (to allow flex).

 

Thanks a lot for a response... I kind of thought it would defeat the purpose, but being that the flange on the HKS dp is a lot thicker than the stocker, I wasn't sure.

 

Okay, so the torque wrench thing is totally out of the question on these spring bolts. 37 ft lbs may be correct for the stock downpipe, but for the HKS one it can't be right. Way before they get that tight they stop threading. IE: the springs are pretty much fully compressed at that point and you can't go any further. Anyone who installed the HKS downpipe themselves please tell me how tight to tighten my spring bolts. I can't read the damn Japanese instructions.