DIAMOND EYE K4122S-RP CAT BACK EXHAUST SYSTEM FOR 06–07.5 SILVERADO/SIERRA 2500/3500 4 INCH SINGLE PASS NO MUFFLER STAINLESS

DIAMOND EYE K4122S-RP is a 4.0" T409 stainless cat-back exhaust for 2006–early 2007.5 Chevy Silverado / GMC Sierra 2500/3500 6.6L Duramax (LBZ). It routes single-side (passenger) and ships without a muffler for maximum flow and an aggressive tone while retaining the factory catalytic converter location. Designed as a direct-fit, bolt-on upgrade using OE-style hangers and mandrel-bent tubing.

FAQ: WILL THIS FIT MY LBZ?

Yes—this system targets the 2006–2007 (Classic) LBZ trucks. If your build is 2007.5+ LMM, use an LMM-specific kit. When in doubt, match by engine VIN code and build date.

FAQ: DOES IT INCLUDE A MUFFLER?

No. The -RP variant is the race profile (no muffler) version. If you prefer a stainless cat-back with a muffler for 2006–2007 LBZ, consider the MBRP alternative below.

FAQ: WHAT SOUND/EGT CHANGES SHOULD I EXPECT?

Deleting the muffler and moving to a 4" mandrel-bent system typically sharpens turbo whistle, drops backpressure, and can help reduce EGTs under load compared to stock. Results vary by tune, load, and altitude.

Fitment Details

• Platform: 2006–2007 (Classic body) Chevy/GMC 2500HD/3500HD, 6.6L Duramax LBZ (all cab/bed lengths)
• Layout: Cat-back, single side exit (passenger)
• Tubing: 4.0" T409 stainless, mandrel-bent
• Emissions Note: Retains catalytic converter placement (cat-back).

Cross-Reference / Alternatives (MBRP-only)

• MBRP S6012409 — 4" T409 stainless cat-back (with muffler) for 2006–2007 LBZ.
• MBRP GP010 — 4" aluminized tail pipe (01–07 classic). Useful for mix-and-match repairs.
• MBRP T5124 Tip — Polished T304 5" OD, 4" inlet clamp-on tip to finish the system.

Specifications

Key identifiers verified via distributor/manufacturer listings (UPC 841963101584). Shipping weight/dimensions reflect typical boxed cat-back kits.