I tried searching but all i could find among the clutter was engine swaps.

Basically my question is will an s5 turbo+manifold bolt right onto an s4 turbo engine fine, without having to do any modifications except plugging up the twin scroll system?

 

Yes. If you have the series five turbo oil drain line with the S5 turbo assy you have. I *think* there's a difference b/t S4 and S5 oil drain line lengths.

 

The S5 line is a little longer since the turbo sits slightly different and the front cover is a little different too. Using the S5 line should work, but there may be a little more of a bend than if you had the S5 cover.

If it still doesn't fit with the S5 line, bolt the S5 turbine housing onto the S4 turbo and run it like that.