What's better than momentum? Mo' momentum.

Let's take a closer look at five of this past week's biggest scorchers.

Company

Sept. 30

Weekly Gain

My Watchlist

Harleysville (Nasdaq: HGIC) $58.86 88% Add
Pandora Media (NYSE: P) $14.65 36% Add
China Zenix Auto (NYSE: ZX) $5.20 22% Add
Generac (NYSE: GNRC) $18.81 21% Add
KiOR (Nasdaq: KIOR) $20.74 21% Add

Source: Barron's.

Harleysville climbed 17% two weeks ago, as Bloomberg reported on buyout chatter indicating that auto and home insurer Nationwide Mutual was eyeing a bid. Well, the rumor was right. Nationwide's paying a juicy premium to acquire Harleysville, making it last week's biggest winner by far.

Pandora rose every single trading day last week. The music-discovery site revealed that Pandora will be available in every Hyundai Veloster as a free standard feature. Pandora also revealed key listenership gains in several major markets.

Pandora went public earlier this year -- and so did China Zenix Auto. The Chinese maker of wheels for commercial vehicles had to settle for going public at $6 several months ago, well short of its original pricing range between $9.50 and $11.50. The stock is still trading below its $6 IPO price, but Zenix bucked the trend of cascading Chinese equities last week to bounce back nicely.

Generac Holdings powered up its shares by juicing up its expectations. Hurricane Irene and other powerful storms have created electricity outages that turn homeowners and businesses to Generac's power generators. Generac now sees residential sales climbing 50% for the third quarter and 15% to 20% in the fourth quarter. It was previously guiding toward flat growth on the residential side.

Finally, we have KiOR climbing on the week. KiOR's technology turns biomass into renewable crude oil. Investor interest in alternative energy in general -- and biofuels in particular -- comes and goes, but KiOR has managed to drum up a $2 billion valuation, even though analysts don't see it actually generating revenue until next year.

It was a great week for these five stocks. Now let's see if they're up for an encore.

Which of these five stocks do you think will continue to move higher? Share your thoughts in the comment box below.

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Longtime Fool contributor Rick Munarriz calls them as he sees them. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.