Yeah! Sedan indeed. Yeah! Auto.
BTW, on our club's dyno day all coupes were running between (if I remember right) 230 and 236. There was even a member with test pipes and exhaust. Again, 6 horsepower difference. I don't even know if you can honestly say that 6 horsepower is truly a gain or just a difference in the engines.
I do believe, however, that just by opening one thing (exhaust or intake), you will not gain much since you are still bottle-necked elsewhere. So, we'll see what the headers, high flow cats and Crawford plenum do. There has to be a little more HP somewhere. BTW, I am also planning on the underdrive pulley and am also working on installing an electric fan in place of the engine driven fan. I think this is where most of the difference in HP betweent the coupe and sedan lies.

 

$2000 for 20-30 hp, I have a hard time thinking this is the best way to go.

I think twin turbos are the way to go. Jotech got over 400 to the ground on two different Zs. And at 8 psi I think they got in the 380s.

Now of course you'll have to upgrade the internals before too long. But you'll definatly be on your way to having a real monster.

If you must stay NA, I'd say go with the Z tube, coilovers and sways. And if you don't have brembos already, upgrade the brakes.

 

Well Canton_g35 if someone wants to keep the stock warranty in tact, this may be the only choice. I know people who have paid over $6000 for the Vortec Super Charger and install and are getting near 100hp at the rear wheels, but they do not have a 5 year 60,000 mile engine warranty any more. Plus with the detonation problems people have had with the initial ATI units, I'd be concerned about losing the mod money and then having to pay some awful amount of money for a new engine ($5,000-$10,000 with labor and installation I'm guessing). For me the $1700-$1800, for what I'm "hoping" to be as much as 320bhp (at the crank) seems the most logical way to go. At least it does for someone on my budget.

Also, you light heartedly mentioned rebuilding engine internals and that's not cheep. I'd guess $5,000+ so add that to the cost of your turbo and installation ($7,500-$10,000-ish) and you're approaching an amount over $100.00 per rwhp, albeit you have a much faster car, unfortunately there's still no warranty.

Also, I know many E46 M3 owners who'd give there right arm for the ability to pay $2000 for 20-30rwhp, so it's really not that bad.

 

There was a reason why I didn't mention any of the SCs. And lets face it, even the Injen or Nismo CAI could void your warranty.

And there is nothing light hearted about rebuilding the engine. When your done with both the top and bottom it'll probably be closer to $15,000. But you'd be over 500 hp. blah blah blah I don't want to start an argument over this.

I just don't think headers, cats, cat-back, intake plenum + others are worth it for a 20-30 hp gain.