yea 3.5" downpipe is all you need and no need for moving anything around. I have a 4" magnaflow downpipe and I didn't have to do anything special to get it in. It certainly wasn't easy but no tools were needed for actually fishing the pipe up to the turbo.
3.5" pipe shouldn't be too bad but you just need to pay a little attention to where the up pipe and downpipe cross (most of the downpipes have a flat spot in them at this point.) Also the transmission dipstick may come close, other then that its pretty straight forward.