John,
If you are going into a dual-ported muffler, I would use 2" straight pipes and put a cross-over or "T" section where the resonators were. This would quiet any remaining popping noise after the cat that straight pipes, alone, would no longer stop.

If you want it especially quiet and/or going into a single-ported muffler, I would recommend high-flow glass-packs in place of the original resonators (just as you mentioned.)

Cheers, Andrew Seidel.

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