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Old 10-21-2021, 09:39 AM   #1
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yeloduster's Avatar
Workhorse Chassis Owner
Join Date: Sep 2017
Posts: 1,093
Insurance against Cracked Manifolds!!!

I have had several trucks that hauled heavy loads. Every one of them eventually developed cracks in the exhaust manifold(s). I have a 2003 W20 with the stock exhaust manifolds and think cracked manifolds is a matter of WHEN not IF I will have a cracked manifold.

Reading on this forum and my own research it seems that replacement manifolds and exhaust headers for the W20 have become rare as hen's teeth. I decided that I would get some headers if possible for insurance against a future manifold crack.

I researched header availability and find that ONLY Doug Thorley still makes headers for the W series Workhorse. However, they are out of stock and only schedule a production run when they have enough orders to justify the setup. They accept your order and place you on a waiting list. They will charge your credit card when the headers ship. Don't order directly, contact them at: Tell them you would like to get on the waiting list for a set of THY-312 headers for a 2001-2011 W series Workhorse motorhome. They will probably respond quickly telling you how to get your headers on the list.

Banks still makes the headers for non-EGR applications. In other words for 2004 and newer W series chassis. However the Banks headers are ~$400 more.

I've ordered Doug Thorley headers. I expect to see them in 4 to 8 months! That's OK, I don't yet have a cracked manifold and can wait. With the headers no cracked manifolds and as a bonus more performance for sure and maybe slightly better fuel economy (NOT).

The more that are ordered the sooner we will all get our headers.
2003 34' Georgetown on W20 Workhorse Chassis. UltraRV power mods. Front Sumo Springs, Rear P32 Sumo Springs, UltraRV Track Bar.
1998 Jeep Toad.
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