It doesn't matter what kind of engine you have, headers will always make a positve difference and the sound is incredibly delicious. 10% power increase guaranteed !
Don't doubt it unless you try it.

I'm talking about exhaust manifolds not heads

i guess i didn't read that closely enough.

But, i would still say that you should save up for headers rather than going part way with the "ported manfolds"

Of all the mods on my car, the TOG headers impressed me the most! YMMV

Cheers,

You guys have boost too.

SC or NA it doesn't matter.
Headers will always improve an engines efficiency and create more power and torque throughout the rpm range.
The key on NA engines is to keep the tubes small.
TOG headers are small tube design. TOG have just come out with a larger tube design that are better suited for the big dogs.
SLP pipes are a little smaller and should be better for NA engines.

the key on n/a engines is samller primaries and equal length primaries.
The headers that come close to that description are *&* headers.

the reason i said you guys have boost is because your engines respond to mods better. headers compared to pems on a boosted car will see a huge diffrence
but on an n/a car the diffrence isn't going to be as noticable or worth it unless you have some serious valvetrain/cam mods and you're flowing more.
The headers especially SLP/TOG will make a stock n/a car loose a bunch of low end, pick up hp in the higher end, but the higher end hp isn't going to be taken full advantage of without a cam or maybe rockers.

all i'm trying to say is don't spend $400 more than you have to for a few hp that pems won't give you in a n/a car. i say 400 cause *&* are $5xx.xx and welding is necessary.
That 400 can get you rockers and alot more hp than the upgrade to headers.

I'm just thinking in terms of hp/$