If Bart Mroz was pushed to give you a piece of advice, it just might be to limit yourself.

The founder of the recently re-branded SUMO Heavy Industries says a lot of firms doing web work get caught up in trying to do too many things and come up short doing them well.

“We started as a web development company that did all kinds of things like brochure sites and app development for different clients,” Mroz tells Technically Philly. “Then we decided to only do e-commerce work — the best decision that we made.”

In March 2008, Mroz co-founded round3media and by last November, Mroz had learned his greatest skills were focusing strictly on e-commerce site development. After his two partners in round3 wanted to work on different projects, Mroz started anew, launching e-commerce heavy SUMO with new partner Robert Brodie and creative director John Suder.

With a new name and a freshly announced, local client, Mroz is — and forgive us for this — entering the dohyō and fighting to build his company’s name as the top e-commerce development company in the region.

Last month, SUMO signed Robinson Luggage, the 80-year-old, Pennsauken, N.J.-based luggage retailer with a high-profile South Broad Street location at Walnut Street and a high-traffic e-commerce site. They’ve also launched Philadelphia’s first e-commerce specific meet up group.

Bart Mroz, co-founder of SUMO

Mroz, who emigrated from Poland at age 12, says working with companies from the region remains a priority. His team, which, to date, works from home, is local too. Mroz lives in Headhouse Square, partner Brodie in Levittown and Suder in the Northeast.

The three have already had successful projects, of course.

Mroz says the online store they designed and developed for Schoppy.com, which is undergoing additional work to date, brought a 300 percent return on investment in a single year on what the company paid for the project.

So, Mroz, one of the first full-time members of Independents Hall and a co-creator of the Open Chefame event, says it’s no mistake they’re choosing to re-build in this market.

“For us it’s important to be in Philly,” Mroz says, “since it is a emerging market with technology [and a location] that we can use for all of our clients.”

Every Monday, Technically Not Tech will feature people, projects, and businesses that are involved with Philly’s tech scene, but aren’t necessarily technology focused. See others here.