Pepsi-Cola, just like Coca-Cola, started out as a quasi-medicinal tonic that was developed and sold in Southern pharmacies during the late 19th and early 20th centuries. Given that timeframe, it's hardly shocking to learn that in the 100-plus long years since Pepsi's inception, its recipe has undergone a number of revisions.

Pepsi-Cola, just like Coca-Cola, started out as a quasi-medicinal tonic that was developed and sold in Southern pharmacies during the late 19th and early 20th centuries. Given that timeframe, it's hardly shocking to learn that in the 100-plus long years since Pepsi's inception, its recipe has undergone a number of revisions.

One of its formula alterations (and I'm not singling out Pepsi here; Coke and in fact most soft drinks are in this same boat) has lately been blamed in public forums for sending people back to the pharmacy - only now to get real medicine to deal with weight-gain-related illnesses. Yes, I'm referring to the controversial usage of high fructose corn syrup as a soda-pop sweetener.

OK, I'm not going to step my foot into this particular health debate, but rather I'm going to tip my tongue into the taste differences (if any) between HFCS Pepsi and old-school Pepsi. The reason this is possible is because, for a limited time, Pepsi is offering products made with "real" sugar (yes, we live in an age when making things with plain old sugar is a cause for nostalgia and publicity launches).

What I tried: "Throwback Pepsi" and "Throwback Mountain Dew" ($1.49 each)

The Pepsi Challenge: Frankly, I was surprised at the stark differences between the two same-named quaffs. Pepsi regular (or no-back?) had longer lingering and fatter bubbles, and it also had an insipidly sweet flavor with a syrupy and flabby aftertaste. In contrast, Pepsi Throwback was lighter, crisper, far more focused and it had a comparatively pleasant and refreshing finish.

Do the Dew: Another high-selling son-of-the-South soda pop is Mountain Dew, which has been around since the 1940s. Playing down the hillbilly image it once reveled in, Mountain Dew - which is produced and distributed by PepsiCo - rebranded itself for the skateboard-and-video-game set, with gaudy gamer graphics of floating mountain peaks. More recently, it's eliminated most of its apparently cumbersome vowels and is therefore now simply known as "Mtn Dew."

Well, amusingly, the hillbillies are back. Because exactly a la Pepsi, Mountain Dew Throwback has recently been released (for a likewise limited time), and its retro bottle features a hilarious moonshine-jug-handling Jed Clampett-looking dude smiling as the jug cork bullets its way through his well-worn hat.

Tastewise, I found the differences between the two Dews to be similar to that of the two Pepsis, if less dramatic. The main discrepancy was the faint presence of actual orange juice in the Throwback Dew, as opposed to the wholly icky fake citric flavor of the new Dew.

Would I drink any of these again?: I might have a Throwback Pepsi on occasion. But I'd approach the drink as one should - as a treat, and not a way of life.