Depends on your tastes, but for OEM feel, 4-2 (2-1 x 2) or 4-4. The 4-4 is more throaty and gurgly. A proper tuned 4-2 with proper volume should be much more subdued. For stock looking, I personally havent seen a 4-1 that looks correct.
Personally, On my one piece muffler/header, I carefully removed the OEM weld and put on aftermarket slip-on