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Good question. Now for the multi part answer...
On a normally aspirated engine there are fewer gains than on a supercharged engine.
A tune is normally required to get the best results.
The stock head breaths rather well, at 189HP it is not pushing it's breathing limits very hard.
Due to the fact it is a multi-valve engine, with injectors instead of carb, a smooth intake tract is better than a swirl polish (which is the old classical way to finish the intake tract), take your heads to a place which understands this.
If you are getting a tune, consider updating your cams too.
 

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Illegal Alien
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5,258 Posts
Any benefit to having a NA's heads ported and polished?
Question, have you tuned your car yet? The gains will be much more substantial and much cheaper. In fact I would follow the tune, intake, header path to completion first before thinking internals. And internal look for bigger jumps like the big sleeve kit and then because top is off, maybe polish.. but to just open to only polish for maybe 5 hp gain,why. As to cams.. replace with what... again just play with the tune and adjust the VVT.
 

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And internal look for bigger jumps like the big slave kit and then cause top is off maybe polish..
So to paraphrase: He wants you to get some Big Polish Slaves to push your car ;)
 

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Illegal Alien
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Not at all what I meant to say but auto correct does point us into an alterative power source. I said start with a tune. It will give you single biggest gain.
 

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Sorry Julian73, I could not resist... It looked like an auto-correct on the word "valves". My sense of humor can be strange in the morning, before Coffee. After the coffee, it gets even worse.
 

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Illegal Alien
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No problem, I wrote mine, read and responded to yours while in car to airport.. ok I wrote mine in the line at Starbucks. But I too misread yours, overlooking your humor as auto-correct as if I was pushing the BWR big sleeve kit.. I like to post with humor on this site, but I need coffee to kick in to soften the issues of the day. Only problem with BPS power is that on the downhill runs you need to rake them on board and the extra weight kills the handling at the bottom if the corkscrew.. I need to work up an alternative carrying device. I tried letting them run alongside but the power lag is awful coming out at the bottom.
 

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I am currently working through maxing out my NA as much as possible. There is plenty of power to be had-its not necessarily cheap to do the full shebang (intake, tune, headers, coatings, exhaust, decat, etc) but you will certainly see a safe, reliable and repeatable jump in power.
 
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