sorry for the y-pipe thread, but i was curious if anyone knew knew the size of the bolts from the y-pipe to the cat. those two 14mm i think. i want to go and get them before home depot closes in 25 mins. can anyone help me? i know there was a post on this just a few ago, but i can't find it. sorry for my laziness. would really be appreciated!!

 

yes they are 14mm

 

thanks, but i knew that part already. what about diammter and thread? was it 3-5/16 or something like that? and will 2" long work?

 

y pipe to cat is 12mm the y pipe to header is 14mm at least it was like that on my car. the 3/8"-16 threads were a little bit so i drilled out the holes in the cat a little to make them fit. and i got 1 1/4 inch bolts they worked out perfect u can even get awat with 1 inch bolts easily

 

2" is too long, I bought two 1 1/2" and one of them was too long, so I used a 1" on one side and a 1 1/2" on the other side. The hardware store I went to did not have 1 1/4" otherwise I would have used those.

 

On my car, the only time I used the 12mm socket is to remove the two screws that holds the Y-pipe in place near the transmission/oilpan area.

 

well the cat bolts on my car were 12 mm i just installed my y pipe yesterday. maybe its diff on the I30?

 

Dont you have to use a certain grade of bolt?

 

nope. I picked out bolts from a local Ace Hardware. They fit right in and sit tight.