Curious on how these are held in place, are they pressed in, welded in ? Usually the headers I have dealt with have these in place solidly, not just held up there.

 

they just slide on when they are new. After they have been on for a while they do stick pretty good though. You can usually pry them off with a flat blade of some sort.

 

Bailhatch is right. The donut just slides onto the header flange and the cat or test pipe holds it in tight when you bolt it to the header.

 

Thanks guys

 

What is the purpose of these?

 

Better seal

 

yep, can be had at any local autoparts store for a few bucks.

 

When i replaced my header i was cheap and just reused the old one....it was cracked, etc so i just used electrical take to hold it together till the exhaust was tightened up.....no leaks.

 

Sorry to threadjack but i have a question along the same lines as that.

If i were building a complete exhaust and i had a 2.5" pipe on the header exit what parts would i need to bolt it up to the midpipe? I am assuming i can have a flange welded to the header and one welded to the midpipe with a donut in between. But would i need a flared midpipe to butt up against the donut if the midpipe piping was 2.5" as well? Or just a straight 2.5" with no flare?

 

I would flare the mid pipe or put a collector flange on it.