just got my s4 tII that was sitting in this guys back yard for a couple years. there seem to be alot of s5 engines on ebay and I was wondering if there were any writeups on the swap.

 

there are writeups for it.
http://www.rotaryresurrection.com/ro...ries5swap.html

That link should work.
I would personally not buy an ebay motor but that is just me. I would recommend Corksport because their prices are good and they check their engines well. I know there may be a little wiring to switch to use the s4 electronics with an s5 engine. To use your existing ECU and other electronics I believe you would need to swap the s4 front cover onto the s5 engine so you can use the manual OMP. You can swap the s4 throttle body onto the s5 upper manifold so that you can use the s4 tps. You also will need to use the s4 map sensor and maf sensor. There are probably some other odds and ends.