Can someone tell me the size of exhaust manifold bolts, nuts, and washers that works with the 420A and the HRC Turbo Kits. On the Road Race Engineering website, there are two sizes 8mm and 10mm - which works with the 420A?

Thanks,
Kurt

Also, please include how many are needed. Thanks.

The stock ones are 10mm. Don't know if that helps but you don't have any other replies so...

I just picked up a set from RRE this past weekend.

Unless I am wrong, you will only need the 8mm studs. the 10 mm studs are for the outer bolts of the 4g63 manifold, and is not applicable to ours. I would just purchase the whole set as I don't think Mike will want to part it out and charge you partial price.

I have yet to install them on my car so I can not comment on how they are.

chances are you will only need 6 (four in the center, and the two right next to the center, the harders ones to put on). Everything else you can just use the old studs or allen head bolts.

hope this helps.

Thanks. I am assumming the set from RRE contains the following.

Qty
4 10 mm nuts, studs, and washers
4 8 mm nuts, studs, and washers


From what I have read in the Mitsubishi shop manual, our existing manifold on the 420A is 8 bolts. The 8 mm RRE bolts would be used only on the inside four where the turbo would sit correct? The four outer bolts can be either the allen or the existing bolts?

the head is setup for 8x1.25 studs, I just had to helicoil a few so thats how I know. Got to any good machine shop or parts shop, they'll have a wide variety of studs for about 1.50 a piece for grade 8

I think you got it.

I inserted one of the GST 8mm studs in my block, and it fit with no problem. I think they are way better than the allen bolts that Hahn supplied us.