ANDREW Voudouris was only 15 when he joined his older brother, Steve, then 17, and their good friend Chris Francy in launching an online company called (pronounced ex-oxide) in his parents' garage.

They began by selling custom-built computers - and sold them pretty quickly.

The company soon morphed into a computer-accessories store, selling everything from elaborately designed cases to PC tachometers, a "speedometer for computers" that the guys invented to measure how hard a computer is working. The morning after a high-profile technology Web site did a post about the tachometer, 500 or 600 orders poured in, and Xoxide took off.

Over the next few years, while the Voudouris brothers and Francy, also 25, graduated from Marple-Newtown High School, Xoxide branched out into multiple online stores, selling everything from computer extras to automotive parts, from beauty supplies to aquarium accessories. Eventually, the company outgrew the Voudouris' home and moved, first to a leased 5,000-square-foot warehouse and then to a $5 million, 45,000-square-foot building that the guys purchased with the help of an SBA-backed loan.

Fast forward to 2010. The partners have sold most of the company's online stores, liquidated their computer inventory and sold the domain name Xoxide.

The three are now owners of TURN5, which exclusively sells auto parts and consists of three online stores: American Muscle (which sells Mustang paraphernalia and brings in 90 percent of the company's revenue), Corvette Guys and American Trucks. TURN5, with 110 full-time employees, operates out of about 175,000 square feet in Malvern.

In just under 10 years, the Voudouris brothers and Francy have gone from storing computer equipment in a backyard to generating $40 million in revenue in 2009. They were also named 2009's National Young Entrepreneurs of the Year by the SBA.

Andrew Voudouris chatted with the Daily News about their wild ride.

The challenges of expansion: As the company grew, the guys started storing inventory in the basement as well as the garage of the Voudouris home.

The family bathroom became the company bathroom, and the kitchen doubled as the break room. While the owners went to school during the day, (all three have started college but are now deovted solely to the business) eight or nine employees worked at the house, and 18-wheelers navigated the residential street to make deliveries (and destroy neighbors' sidewalks). It was only a matter of time before inventory took over the backyard as well.

"We'd run outside with all these tarps and cover everything," Voudouris says. "I used to know a lot about the weather. . . . But stuff would get rain damage if we didn't run fast enough when it started to rain."

How Mom and Dad made it through: Voudouris' mom, a teacher, wasn't crazy about having Xoxide employees and merchandise in every nook of her house. But she was always supportive, Voudouris says. His dad, who later purchased Xoxide's beauty-supply store, was downright giddy.

"My dad is a small-business owner, and I think that might have been part of his excitement, too," Voudouris says. "If we did something big, we'd ask him, 'Do you think we should do this?' We didn't realize it until later that he just said yes to absolutely everything. . . . We told him later, 'We always took your advice seriously.' He said, 'I didn't have any advice. You'd ask me something, and I'd say yes.' "

Not sure? Just Google it: As the business expanded, the guys - who have no formal training in business or marketing - learned virtually everything they needed to know on the Internet.

Through online research, they uncovered untapped markets and figured out search-engine optimization to make sure customers found Xoxide's online stores first.

"We realized our success with computer parts had a lot to do with online marketing, not the products themselves," Voudouris says. "One thing was search optimization and drawing people to our site. . . . We just looked at what people were searching for and where there wasn't a lot of competition: beauty supplies, car parts for Mustangs, Corvettes, aquarium supplies, pool-table supplies, stuff for dogs and cats . . .

"Everything we've done has been stuff that we learned online one way or another. We'd go to Google and type in, "How do you get more people to your website?" . . . When we were trying to determine how to lay out a warehouse, we typed in, 'How do you lay out a warehouse?' It's incredible the stuff you find online."

It's all about how you market yourself: "We attribute a lot of our growth to our online marketing and trying to make things significantly easier for our customers," Voudouris says. Of his auto business, he says, "We were one of the first companies to stock products in our warehouse, so when you place an order, it ships that day. Sometimes it takes one to two months to get a product through a catalog . . .

"We brought a lot of new ideas to an industry that operated in an old-fashioned way, like investing a lot of time and money into photographing our products. It really changes who our audience is. We don't need a serious car guy, just someone who owns a Mustang.

"And we offer free shipping on everything. . . . It is the biggest promotion we run. It costs us $2 million a year, but we really market it. It's written on everything we ship and market."

Why success doesn't really change who you are: It's not every day that a 23-year-old finds himself part-owner of a multi-million-dollar company. But Voudouris spends virtually all his time at work or with friends, and he's still more likely to be found in the 400-level seats than in a private suite at Citizens Bank Park.

"I don't do much with the money because I'd rather be friends with all the people I'm friends with and fit in with everyone I know," Voudouris says. "My lifestyle is pretty modest. The greatest thing is the convenience of not having to worry about money. I don't do a lot of crazy things, like going to Jamaica every weekend. Every once in a while, we'll have a good time."