So my stock exhaust manifold on my 2000 cracked the other day. I have a 98 with a cracked block that I'm robbing the manifold from. The one I'm robbing is a 3 piece ATS. Problem is,  ATS manifold has 4 studs in it, while the stock turbo has 2 studs in it. Which one would you guys drill out the holes on to get them to mate together? I'm not ready yet to put the compounds from the donor truck on my 2000 yet. 

Be aware the 3 piece could leak at the joints. This typically for most i suggest the factory manifold again. Cracking means someone abused the truck ran it hard and didn't monitor EGTs. Last year a replace a manifold be cause it shrunk 1/2 inch could be used because the owner came in for overheat but had no boost or EGT gauges and fried the exhaust manifold. The owner had no clue the boost was low EGTs where high enough to bury the gauge. Pyrometers save exhaust from cracking.

I have a pyrometer and a boost gauge. It's a 24 year old **** box.  I'm not always the nicest to it.  But the previous owner was definitely harder on it. Stock manifold was pretty damn rusted too. The 3 piece came off truck with compound set up and never had any problem. The compounds are going to go on this truck I think, after it's warm again. Bigger one is a 109mm off of a 14L Cummins. It's all just money, right? 

1 hour ago, Lund1990 said:

The compounds are going to go on this truck I think, after it's warm again. Bigger one is a 109mm off of a 14L Cummins. It's all just money, right? 

 

Well... Bigger turbos spool much slower. 109mm is going to be too big for sure. Heck most people have issues with spooling just a 71mm compressor on the street. One of the few reasons I kept the HX35W is the quickness to spool and the fact of my exhaust brake on the back of the turbo. I'm looking to upgrade even like 62/68/14 Turbo if possible but would require a full exhaust brake replacement too., Ouch!

That's the exact reason why I'm still running the stock turbo.  It's nice and snappy. Donor truck was set up for towing large loads and doing pulls.  It also had propane injection before. The smaller turbo is an s300 variant. Haven't done much research to find sizes. I've actually been contemplating adding a belt driven supercharger too, just for the instant boost. I saw a video where a guy had taken one from a gm 3800. It actually seemed like it quirked pretty good. Plus it provided boost at all times,  even just a little at idle.