What are your end goals? I lot of folks (myself included) have had excellent results with cast manifolds like the ones Symtech sells. they're relatively inexpensive and won't crack like a lot of tubular manifolds will over time.

For refrence one of the only reason tubular manifolds crack is if they were not fabricated properly (not purged) or improperly fitup, or improper welding technique. not purging leaves a black sugary nasty crack prone bead on the inside of the part. Some tubular manifolds will never ever crack. Also some using 16g stainless instead of sch10 can also cause premature failure.

Well currently I am running about 300 to the wheels and that's very conservative for the break in of the new built motor. But I am looking to up that by a lot and really wanted a tubular instead of log style. I saw the Xtreme fab ones and they look to be really good quality and well made

I know nothing about the 420A stuff but if gou can find a good quality welded one go for it, youll spend around 500 new for something that isnt absolute crap.

I understand that. Honestly money is not an issue at all. Everything in my car was the most quality I could find. It is not my daily driver so I try to just save for the best that I can get

Good call

urbansmoker1 said:

For refrence one of the only reason tubular manifolds crack is if they were not fabricated properly (not purged) or improperly fitup, or improper welding technique. not purging leaves a black sugary nasty crack prone bead on the inside of the part. Some tubular manifolds will never ever crack. Also some using 16g stainless instead of sch10 can also cause premature failure.

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Does it not also have to do with not having them braced? Hanging some heavy turbo off of one and then no supporting framework could leave to cracks too, right?

OP, there's a shop local to me that does custom manifolds for practically any application. I'm thinking something like that will run 600+, but I'm not sure. Maybe there's someone similar around you that will build what you're looking for from scratch, or I could give you his info.

Braces are used if the gauge is thin. Or if there are defects in the weld it will help against cracking, A not purged weld is basically burning the metal and taking away its corrosion resistance, (stainless). weld filler material depending on the application can start at 70,000 psi tensile strength, so if a properly welded manifold is had, it should have no problem holding a large turbo. The studs in the head would pull out before the manifold cracked, take my stm manifold for example, sch10 304 stainless fully purge welded no braces what so ever is holding up my hx40 .70 ar bep housing custom o2 housing and down pipe with a 44mm wastegate and the dump tune, it won't crack. And they have a lifetime warranty guaranteeing that as well. Because the fabricator there (cory bowers) knows how to weld like a mad man. I'm in welding school right now and in learning about defects in metallurgy. (14 weeks left til grad)

To put it simply, a crack in a weld (which is the absolute worst defect), is simply the welders fault, not the materials fault. Now there are such things as defective propertes of the base material, but thats rare and most of the weld faults are the operators fault.

I live near Milwaukee, WI and there are shops all over the place doing custom fab work. The problem is that I haven't heard a single thing around here about the 420a. And as far as buying online there are only a couple options and the Xtreme fab mani looked very nice but no idea what happened to that site. I may end up just doing some local research and see who has been doing good work and try to talk to some people in the area who have some custom mani's. Always a struggle trying to find the things I want for my car because there is about 20% the amount of parts offered for the 420a vs. the 4g63 but it is always fun to see people face when they find out that its a 420. Do any of you guys know of any online companies that I could contact about making a custom one?