2003-2007 5.9L Cummins S400/Stock Twin Turbo Kit

Compound power for the third-gen 5.9L

This kit puts an S400-frame turbo in front of the stock-style Holset to make a compound pair. Wehrli rates it as capable of about 1000 rear-wheel hp, depending on turbo and fuel system choices.

It is aimed at tow rigs and work trucks that want more power and tighter exhaust-temperature control while keeping stock-like turbo response. Wehrli's suggested pairings run from an S475 over a stock Holset (up to about 750 rwhp with supporting mods) to an S480 over a Stealth hybrid (up to about 1200 rwhp).

Who it's for

5.9L Cummins owners who tow and want a large, drivable power increase.

Key specs (per Wehrli)

What's included

• 5 in. intake with dry filter and pre-filter cover
• Stainless oil feed and drain lines
• 4 in. downpipe and 3 in. hot side crossover pipe
• 3 in. cold pipe linking the two turbos
• Silicone boots and O-ring seals
• V-band and T-bolt clamps
• Heat wrap with clamps, plus the install hardware; powder-coated finish

Fitment notes

• Fits 2003-2007 Dodge/Ram 2500 and 3500 with the 5.9L Cummins.
• Built for the factory exhaust manifold. With an aftermarket replacement manifold (for example a Steed Speed T3), the manifold must be sent in so the kit can be built around it.
• Wehrli says this kit needs custom tuning to run correctly.
• California: Wehrli does not ship this part to California.

Professional install available at Powertech Diesel, Idaho Falls — call 208-542-7793.