USP Marine Tuning Ultimate Performance Kit for Mercury Verado 350-400 Engines

Description

Questions what the kit does? Watch this explainer video first. 

How to install cowling.

How to install boost pipe kit.

⚠️ Important: The MAX+ Performance Top Cowling ships in primer and must be painted to your color of choice before installation. Do not use heat or bake to dry — this will warp the cowling.

This is the most complete performance upgrade available for the Mercury Verado 350–400HP L6 engine. The Ultimate Kit bundles USP Marine Tuning's four most impactful bolt-on upgrades into one package, tackling boost leaks, airflow restriction, fuel delivery, and engine aesthetics all at once. Buy the kit and save up to 15% compared to purchasing each component separately.

If you're serious about consistent wide-open-throttle performance, cleaner power delivery, and an engine bay that looks as aggressive as it runs — this is the kit.

What's in the Kit

(1) USP Marine Tuning MAX+ Performance Top Cowling (Replaces OEM Part #: 885354T01)

Laser-scanned for exact fitment, the MAX+ Top Cowling is manufactured in the USA using motorsports-inspired injection molding — the same lightweight, impact-resistant material used in competitive racing applications. It's built to handle daily boating and offshore conditions while giving your Verado a distinctly aggressive look. Ships in primer and must be painted prior to installation.

(1) USP Marine Tuning High-Flow Air Intake Pipe (Replaces OEM Part #: 885354T01, 8M6003032, 815504256, 888988016)

The factory plastic resonator pipe is restrictive by design and prone to cracking over time — a known failure point on these engines. The USP Marine intake pipe replaces it entirely with 4-ply wire-reinforced silicone piping (the same spec used in USP Motorsports' 1000HP turbo builds), CNC machined adapters for smooth airflow transitions, and 316 stainless clamps throughout. The result is a +30% CFM improvement over stock, sharper throttle response, and lower intake air temperatures at WOT — plus the refined supercharged induction sound these engines are known for.

(1) USP Marine Tuning Boost Pipe Kit (Replaces OEM Part #: 8M0095505, 8M0095506, 8M0095507, 888988021)

The factory boost pipe is narrow plastic — a known restriction and boost leak culprit that's notoriously difficult to diagnose. The USP Marine Boost Pipe is built from mandrel-bent 2.5" aluminum tubing with 4-ply stepped silicone couplers, finished in a wrinkle black powder coat for an OEM+ appearance. The kit also includes a replacement for the damage-prone coupler connecting the boost valve to the intake manifold — so you'll never chase a mystery boost leak again.

(1) USP Marine Tuning Billet Aluminum High-Flow Fuel Filter Kit (Replaces OEM Part #: 879885K, 879885Q)

The plastic OEM inline fuel filter was never built for serious offshore use. The USP Marine version is machined from billet aluminum, engineered with the same fuel system principles used in high-performance automotive applications, and built to withstand the harsh marine environment long-term. It protects your injectors while providing optimum flow for performance use.

Compatible Engines:

• Mercury 350 Verado L6 (4-Stroke 6 Cyl.)
• Mercury 350 Pro Verado L6
• Mercury 400 Verado L6 (4-Stroke 6 Cyl.)
• Mercury 400R L6

Customer Reviews