I'm not sure what pink stickers you're talking about. I think the STi is ugly, too, but I still like it. Folks have hinted that you might be able to remove the spoiler, but even then, you've still got that gigantic scoop.
You can get the performance package for the 350Z and not have too much of a dropoff from the STi. Something like 13HP and 26 lb. ft. -- a conceivably chippable amount.
I'd also suggest looking at the RX8, but I doubt it'll have enough power for you if these are the two cars you're looking at.
How often do you cart stuff around? A friend of mine has an MR2, which has even less cargo space than the 350Z (1.9 vs. 6.8 cu. ft.) and it doesn't bother him much.
I'm rambling. Let's cut to the chase.
Why is styling important to you at all, ignoring how much it's important?
Why is practicality?
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Bitt Faulk