i was going to get a low mount manifold made by 6boost, for my gt3540 IW that i had,
he said it costs abit more than a high mount, and its not worth wild. As it would be tight as F#$k and the amount of heat being produced in a tight area. Even if you have to pull the turbo out at some stage would be a pain in the arse.
Direct quote from Kyle (6boost)
Keep in mind that in standard form, the factory manifold is only about 4" thick, and the turbo flange points straight at the block. The only manifolds that you can get that will fit in the standard location are those poxy stainless jobs that are absolutely horrid. I can't build you anything in the stock position, and can't see why you'd bother to, as there is no room to fit any type of decent collector. My low mount would be something similar to the one pictured in my thread here:http://www.calaisturbo.com.au/showthread.php?t=107446
I highly recommend you don't go low mount, they are very bad for transfering heat into the engine bay and make working on the engine a pain in the ass. However if you must have a low mount, the price is $1200 inc, and comes with studs, nuts, turbo gasket and lifetime warranty against cracking, defect and failure.