Tri-Y Headers w/ Y-pipes, 1987-94 GM Class A Motorhome, 366-454 Big Block (TH400 transmission)
ITEM #: THY-306Y1-C / THY-306Y1-S-C
Tri-Y Headers with Y-Pipes
1987-94 GM Class A Motorhome (TH400 transmission only)
366-454 Big Block V8
Application notes: TH400 automatic transmission only | Gear selector sequence should be P-R-N-D-2-1 | Will not fit D-port cylinder heads
Header Style: 4:2:1 Long Tube Tri-Y Headers
Finish: Silver Ceramic Coated
Weld Up: Yes, Y-pipe outlet must be welded to exhaust system
Primary Tube Diameter (in): 1-3/4"
Primary Tube Gauge: 14 Gauge
Collector Attachment: 3-Bolt Flange
Collector Diameter: 2-1/2"
Flange Thickness: 3/8"
Bolts and/or Studs Included: Yes
Gaskets Included: Yes
Reducers/Adapters Included: No
Y-Pipe (Crossover) Included: Yes
Y-Pipe Inlet Diameter: 2-1/2"
Y-Pipe Outlet Diameter: 3"
Catalytic Converter(s) Included: No
Quantity: Sold as a Complete Kit
CARB E.O. #: D-540-5
Warranty: Limited Lifetime to original purchaser (see FAQ's for details)
Header Information: Backed by over 50 years of knowledge and experience, our headers are designed to outflow your stock exhaust manifolds by leaps and bounds. Tri-Y (or 4 into 2 into 1) style headers by design will increase the power of your motor across the widest RPM band possible, while increasing your gas mileage potential. That is the beauty of the design, and that is why they are the best street header available. To make these headers last, we built them using industry leading 14-gauge steel tubing with 3/8" thick flanges. To top all of that off, our headers come beautifully ceramic coated to greatly reduce under-hood temperatures and protect the headers from the environment. All 100% American made, and backed by our lifetime warranty of course!
Unless otherwise noted, these headers are designed to fit the vehicle as it came from the manufacturer. This includes components like cylinder heads, chassis, steering, motor mounts, body mounts and bushings, etc. If your vehicle is using aftermarket components, parts from other applications, or custom altered parts, then it is the installer's responsibility to verify fitment.