Product Description
Upgrade your 2nd-Gen Cummins exhaust flow with the MBRP DS9401 4" Down Pipe (Armor Plus T409). This bolt-on T409 stainless downpipe replaces the restrictive factory section to drop EGTs and sharpen turbo response. Built from rugged 16-gauge T409 and backed by MBRP’s Lifetime Warranty, it’s a durable, value-packed choice for daily drivers and tow rigs in moderate climates.
- Series: Armor Plus (T409 Stainless)
- Tubing Size: 4"
- Clamp-on, no-weld install
- Optimized flow for lower EGT and better spool
- Lifetime Warranty (material/workmanship)
Fitment
1998.5–2002 Dodge Ram 2500/3500 with 5.9L Cummins (24-valve). 1998 is a partial-year split—verify 24-valve fitment. Not for vehicles equipped with a catalytic converter.
What’s Included
- MBRP DS9401 4" T409 down pipe
- Clamps and install hardware per MBRP kit contents
Cross-Reference / Alternatives (MBRP-only)
- For 2003–2004 5.9L: MBRP DS9405 4" Down Pipe (T409)
- 98.5–02 full turbo-back (T409): MBRP S6100409 4" Turbo-Back, Single Side
- 98.5–02 turbo-back, no muffler (T409): MBRP S6100SLM 4" Turbo-Back, No Muffler
- 98.5–02 turbo-back (Armor Lite Aluminized): MBRP S6100AL 4" Turbo-Back
- 98.5–02 turbo-back (Armor Pro T304): MBRP S6100304 4" Turbo-Back (T304)
UPC
882963100535
Does this fit early 1998 trucks?It fits the 1998.5 (24-valve) trucks. If you have an early-1998 12-valve, use parts listed for 1994–1998 applications.
Will T409 stainless rust?
T409 can show surface discoloration over time but is covered against defects in material/workmanship. For maximum corrosion resistance in harsh winters, consider Armor Pro (T304).
Is tuning required after install?
No tuning is required. This pipe is designed as a bolt-on replacement to improve flow and reduce EGTs without calibration changes.
Does it include clamps?
Yes—MBRP includes the required clamps/hardware in the kit contents.
