im in the process of building a motor for my drift car and im to the point of building a turbo manifold. i have a custom Vband turbo /Tial 44mm wastegate set-up i sourced from Rado at World Racing and i cant find a deciently prices manifold set up, so im gonna build my own with a little help. talking ot a local guy i know out here who built the manifolds for John Sheppards DSM back int he day, he sugested i use 321 stainless over the more common 304 stainless. i know Mike has used 321 to make DPs for a b15 sentra before so i know hes familiar with it. my question is this. to get my materials together in 321 stainless comes out to about 850 bucks with a month wait time. i can get the same materials in 304 stainless for 250 next day. does the higher temp qualities of 321 justify the 4x cost? can a 304 manifold be made more durable by running extra bolt on bracing to say the block?

If it's just a toy track car that you can trailer home, I'd just go with the 304. Get creative on ways to help support the weight of the turbo and downpipe to help take the load off the manifold. For example, the Evo X turbo has a brace going from the compressor housing to the engine block, and a bracket that goes from the turbine housing to the engine block.

Do not coat or wrap the manifold. If you can run E85, the cooler EGTs will help. And for the cheap cost of the 304, you can build two or three manifolds.

Mike is right in that 321 will probably crack too with enough abuse.  Inconel is the ultimate stuff.  But it all comes down to cost right?  If it were a daily driver car that requried very good reliability, 321 at the minimum.  But since this car sounds more like a toy car and not used for competition (where reliability is also critical), it's up to you if you're willing to accept cracking and the downtime associated with it.  Just realize with 304, it's certain that it will crack at some point.

321 for sure since you'll be using it for competition.  You want the wastegate flow to come off the merge (as close to the flange as possible) at as shallow an angle as possible.