LLI Engineering today has over 100 active clients. The firm works with many prominent corporations, developers/owners, architectural firms, construction firms, and other clients to provide innovative solutions to today's complex problems.

By combining the former name (Larsen and Ludwig, Inc. - LLI) and their expertise, LLI Technologies became the largest Pittsburgh based firm specializing in complex infrastructure systems. The nation's largest technology and telecommunications companies became major clients of the firm. The firm manages many design-build projects for several clients to help meet critical time schedules.

By 1957, Hunting and Dunnells had both retired, and in 1964, Homer Ludwig became a partner with Henry Larsen. Based on their experience with heavy duty structures and the infrastructure systems of buildings used for scientific purposes, the firm became pioneers in designing data centers, telecommunications equipment buildings and switching centers. This new area of expertise expanded the client base to include Bell of Pennsylvania as a major client in 1965. along with Robertshaw Controls, H.J. Heinz, Humble Oil, The Pittsburgh Press and Gulf Research.

In 1947, Davis sold his shares in the company to Henry Larsen, a structural engineer, and the company name was changed to Hunting, Larsen and Dunnells. The client base also began to change, adding more commercial clients, general office buildings, banks and research laboratories to its portfolio expertise.

In 1930, the firm added a new engineering partner and changed the name to Hunting, Davis and Dunnells. As the reputation of the company began to grow, so did the scope and magnitude of its projects. Leading up to and during the World War II years, there was a focus on industrial and manufacturing projects. In that time frame the firm added clients such as the Railroads, the Federal Government, the US Army Engineers and the US Navy to its growing list of clients. Westinghouse, Alcoa, General Electric, Piper Aircraft, Peoples Natural Gas and Graybar Electric were all prominent industrial clients of the time. Many of these companies remain as clients to this day.

An engineer and an architect started a company that would become known for utilizing new ideas and putting them into practical applications for the benefit of their clients. The Hunting-Davis Company was established in 1910 based on the utilization of reinforced concrete as a structural framing system.

During the early 1900's, this new building technology made it possible to build cost-effective multi-floor structures capable of carrying huge loads. Combined with advances in vertical transportation systems (elevators), the ability to create heavy-duty structures that were naturally fire-proof and highly secure caused the appearance of buildings such as the multi-story automobile dealerships, high-rise warehousing and massive multi-story manufacturing structures. A few notable clients during the period included Union Switch and Signal (Braddock, PA), Pittsburgh Plate Glass (PPG), Kaufmann's, Standard Manufacturing (plumbing fixtures) and Cheesebrough-Ponds.