Just the same, Hamlin said, he looks back and realizes now that his plan was based on some misconceptions.  He started the business in the garage behind his home with $100,000 in inventory and by going out a getting involved with every diesel truck forum he could find to let people know about his business.

"The biggest thing that I was surprised about was how difficult it was to capture the Internet buyer," Hamlin said.  "If you're not a major company, the Internet can be a major black hole.  You just don't have enough financial power to compete."

Profits improved when the business moved to a 2,200-square-foot shop on the busy corner of Sepulveda and Stagg in 2003, he said.  "Profits improved even though Internet sales went down because margins went up," he said.  "You need to be able to sell it, install it, and support it.  That's where you make the money."

Hamlin, who said he worked as a plumber for 10 years to earn enough money to open his shop, said he specializes in diesels because he hasn't owned anything else for 22 years.  "I know what I'm good at and I stick to it -- diesel repair and modification."

Having a good basic knowledge of the diesel engine is very important for shops that want to offer performance upgrades, Hamlin said.  "A lot of shops send us stuff to fix because they put in a lot of performance parts without knowing how it really affects the vehicle," he said.

Whether repair or performance, Hamlin said he charges $100 an hour.  "I won't sit here and lowball stuff to get a job," he said.  "If you don't get paid, you won't stay in business."

He said 90 percent of the shop's work is charged at true time but that he does have menu pricing for common repairs such as brakes, water pumps, and Duramax injectors.

Hamlin said he also won't cut corners on parts because it leads to comebacks and because his customers expect the repair to last.  "When you buy a truck, you expect it to last for years," he said.  "When you buy parts, the customer also expects the part to last.  If the first water pump went 125,000 miles, they expect the replacement will as well."

Hamlin said he mainly buys OEM parts with a few exceptions that he knows are very high quality.  "You can't afford to do things twice," he said.  "If you buy quality parts, you reduce the chance that you will have to."

Martin said he buys most of his Ford parts from Galpin Ford, just a few blocks away, because he can get almost anything he needs within an hour.  He said he splits his Chevy business between Rydell and Courtesy Chevrolet, depending on who has it in stock, and buys his Dodge parts from Dependable Dodge because they keep a large diesel parts inventory. 

 
Hamlin's preference for OEM parts also extends to engines and transmissions, he said, and the shop even has a new Ford diesel engine on display at the shop.  "The average diesel engine is $10,000, and that's before it's installed, so the customers wants to make sure it's backed by someone they know."

For aftermarket parts, such as filters and fluids, Hamlin said he buys from a Parts Plus store just a couple of blocks away.

 
"I think one of the reasons we've done well is because I have focused on what's important," he said.  "We need the part as quickly as possible, the price is secondary."  That is especially important because the shop is small and has limited parking, and the trucks they work on take up a lot of space.  "We need to get them in the door and back out," he said.

Hamlin said the shop has one full-time mechanic in addition to himself.  "He's only 28, but he is what I call a mechanic -- a technician is what (a quick lube) calls their oil changers," he said.  "Jerry is a mechanic because he can open up the hood and has the capability and intelligence to take something he has never seen before apart and put it back together with no leftover parts."

The shop benefits from working on the same types of trucks repeatedly and therefore seeing the same problems again and again, Hamlin said.  "Seventy-five percent of what we do on these trucks we do over and over again because trucks are very predictable."

For instance, he said, the shop solves lots of fuel system problems on Dodge trucks, provides a good deal of TLC to Ford Powerstrokes once they pass 200,000 miles, and sees plenty of Chevrolet Duramax owners because they are too complicated for the DIYer to work on.

About 70 percent of Diesel Performance Shops' work is repair while about 30 percent is performance modifications, which range from software upgrades to extensive engine modification.

The first step for most truck owners who are looking for more horsepower is to upgrade the truck's computer software, Hamlin said.  "You can buy 100 HP for less than $500," he said.  "The next 100 HP is going to cost you $2,000 to $3,000."

In addition to being a good deal for the customer, the computer upgrades are also very profitable for the shop, Hamlin said, because they have a good margin.

Hamlin said he uses performance product providers locally and around the country, including Englewood Transmission, Advanced Motor Sports, BMS Machine, Piers Diesel Research, Black Widow Diesel, Diesel Performance Parts, and Premier Performance.

The suppliers that he works with have all been chosen because of their knowledge of the products they are selling, he said.  "I buy from the company that can help me the best if I have a problem," he said.

Hamlin said his focus on quality and service works well because that is also what his customers are looking for.  "I don't replace anything that's not needed," he said.  "I install quality parts and charge a fair price for it, and I make sure that the customers understand that I am looking out for them and their wallets.

"Ninety-nine percent of my customers are men between 30 and 50," he said.  "They want to know what you did, what the cost is, and when it's going to be ready.

"I believe that if I take care of my customer, he will take care of me," Hamlin said.  "I'm working for their referrals. I'm not shooting for today's sales, I'm working on next week and next month.  If you're sitting there working to make the money to pay Friday's paycheck, you're already out of business.  You just don't know it yet."