Does anyone know the bolt sizes for installing High Flow Cats? I bought used aftermarket ones that did not include the bolts. They should have these at Home Depot right?
Also, the gaskets look like they are in good shape, anyone have any issues using there original ones?

 

Crawford Z was kind enough to provide me with the proper sizes for bolting aftermarket HFC.

6 x 10mm, 1.25 thread pitch, 40mm long

(brackets) 2 x 10mm, 1.25 thread pitch, 25 mm long

You can also use your original gaskets.

 

Use new gaskets. You can get them from Nissan or one of our sponsors. I recommend stainless steel with self-locking nuts. If your local auto store does not sell quality hardware, I recommend a marine store.

 

I think I read somewhere that you should use only stainless steel bolts for cats/TPs.. Is this true? Does it really matter?

I ask because it is next to impossible to find 10m, 1.25, 40mm bolts in stainless steel.

 

You can reuse bolts/gaskets. But i would replace them with new.

 

Well, I have to replace them. The bolts on the stock cats are attached to the cats. When I put in a used aftermarket HFC - it does not have bolts. I must buy new ones.

The questions is - Do they need to be 'stainless steel'?

Will Grade8.8 bolts and class8 nuts suffice?

 

You got me. I was only think about aftermarket hfc to Aftermarket. I wouldn't really worry about using stainless steel, mine is just normal bolts.