Yep 04 has no ubend to worry about, just slap the plog on there and be done with it, one of the easiest jobs we have. I had a plog and dp on my sc car forever and I never had any kr issues, and nothing felt any different after I got headers.
And people with a lot more output than I have (smaller pullies) have run just fine on the plog alone. The rear manifold, from everything I've ever read, flows just fine as it just about already has separate runners for each cylinder.
If you really want to compliment that plog, grab an Hv3.. another easy one and there's an actual seat of the pants difference there.
