I'm getting a P0401 Insufficient EGR flow DTC and I plan to unbolt the intake manifold according to TSB 99-085.

Question:

What size bolts attach the intake manifold to the engine block? (10mm, 12mm, 14mm)? Will i need a breaker bar or extensions?

I don't have any metric tools and will need to buy some just for this job. Ideally, I can buy the just ones I need and will have them on hand so I don't get stranded half-way into the job by missing a key tool.

Thanks for any suggestions.