Do some basic breather mods and a tune -- there's a lot of low end grunt to be gained.
Compare and contrast.
That's with a Nismo S-tune axleback (should be comparable to Nismo factory, which can be picked up pretty cheap), K&N panel filters plus Cobb intake tubes, test pipes (or get high flow cats for similar gains), and a tune.
That's it. Factory headers and airboxes.
The tune can also radically improve throttle response.
Seriously, it's got way more potential than you think with a little time and money.