A Miata is a great car. If anyone thinks it makes you gay, you don't want to associate with them.
They are cheap and easy to maintain, and durable enough to not need too much of it.
As for manning one up... if people recognize that it is a genuine performance car, it will quickly get respect. The best way to man one up, is to actually prep it for performance. Don't rice it. Just build it to be what it's supposed to: a track car.
Step 1: Rollbar. You should do this anyway. But there's nothing like a functionally ugly rollbar to tell people you use your car in ways they don't.
Step 1.5: Take your car to Auto-X or track, so that when people give you crap, you can point out that you use your car in ways they don't.
Step B: Wheels and tires. Nothing says "poser" like crappy all-seasons on steelies. Nothing says badass like track tires.
Stage 3: Suspension. Make the car handle better. Miata have a pretty tall stock ride-height. Lowering that makes it look more aggressive. Don't go poser rice-slammed.
Step Pi: Take your car to a sanctioned performance venue, and drive it hard. Then you can legitimately tell people you race.
Step IV: Simple bolt ons. Intake, header, and exhaust. An aggressive, but not ricer-obnoxious exhaust is good.
Step Five: Tasteful Visuals. I like to start with battle scars. I earned them. Then the subtle stickers of a non-poser. Stickers for actual groups like GRM, NASA, and SCCA. I also have little track map stickers for every track I've hit on my door. Subtle, but meaningful. Or, do a good job of painting it in drab primer. Something with more work and care than money. Olive drab is best. There's a guy I know who's done his in camo.
What not to do: Put a wing on. Run crap springs that slam the car goofy low and make it porpoise around. Install an obnoxious fart-can. Drive like a jackass.