Solid

iTrader: (1)

I see that these have a different part number but it is not obvious that there is actually any difference. Does anyone know if they have a meaningfully different fitment or ID/OD? IE, can I bolt NA mufflers up to a turbo Y pipe without issues?

j9fd3s

iTrader: (3)

the turbo mufflers are physically larger, the cans are bigger, but the fit is the same

Dak

What mufflers are you talking about? The stock ones, a specific aftermarket brand, etc. The stock ones will bolt up. Stock replacements should as well. I'm not sure of the difference beyond I think the turbo's piping is a larger diameter. Before they went to the same muffler for both Racing Beat's TII ones had larger diameter piping but would bolt to either stock Y-pipe or their own. Except their Rev TII ones only work with that particular system, It won't bolt to the stock Y-pipe. All other aftermarket currently available are either singles or use their own Y-pipe so they're not compatible with the stock one.

Solid

iTrader: (1)

OEM. Since the heat shields etc are all in good shape on my car but the mufflers are EOL due to internal condensation, I'd like to maintain correctness. I am pursuing lines on good used ones from an 88 GTX and might've found a couple NOS NA ones but no S4 TII ones as yet.