I am building a s475 over the stock he351. Did you do anything to the stocker in a twin setup? I thought I read somewhere about porting the wastegate and enlarging the holes. What about opening up the entry of the of the exhaust so all 6 cylinders can be wastegated?

 

Bump, since I want to know the answers too. Ready to pull my stocker out of the the box it has been in for 3 yrs and do some porting. Anyone got pictures of how much to take off? Doesn't MPI port the stockers? Pictures pls.

 

http://www.atsdiesel.com/additionali...lus%20v1.1.pdf

Pretty good directions on porting out the wastegate. The HE351 already wastegates all 6 cylinders since it has only a single port on the exhaust housing.

HX35's in older trucks had a divider that could be bored out to allow all 6 to be wastegated.