Quick question. I have been looking in my haynes manual to find the grade type of the 2 bolts on the downpipe/catback. I searched and found out that it is a 14mm / 9/16"(might work only 0.012 bigger) bolt, but no luck on the grade. I am upgrading to a ZZP header tomorrow night, and want to go ahead and replace the bolts, and gaskets (though some of you guys might say just reuse the old ones). If not I guess I will find out when I get under the car. FYI being the type of person I am. It would be interesting to find the stress load the engine puts on the exhaust componets. Only if a string gauge went missing at work. End tangent.

 

I would go with grade 8 bolts washers and nuts. They arent too much more expensive and will last longer.

 

That is what I was thinking.