ChoppedThe term chop doesn't have great connotations. After all, no one wants their beloved jalopy dismantled in a chop shop — where thieves take cars to part them out. However, the right type of person might enjoy having a chopped hot rod.One of the earliest modifications hot rodders made to factory cars was to change their body lines. There were multiple ways of doing this, from modifying or adjusting the suspension to alter the stance to channeling, or lowering the body and raising the floorboards. Changes to the vehicle's profile could also change how air flows over the body.Chopping a car was a popular way to alter its factory appearance — you've probably already seen more than one chopped hot rod, even if you didn't know what you were looking at. A chopped hot rod has had its roof lowered by cutting -– or chopping -– out the A-pillars and modifying the windshield to fit into the smaller space.Some hot rodders build a car's entire identity around the chopped roof. The lower the profile, the meaner the look, or so the theory goes. Not to mention less real estate to catches air like a sail. All the better for racing those accursed Scorpions from the other side of the tracks.Frame-offRebuilding a hot rod to your tastes can be a seriously in-depth process, and there are two ways to approach an involved customizing job: frame-up and frame-off restoration. A frame-up restoration essentially leaves the car as-is (pending the removal of certain parts, of course) — generally acceptable for vehicles with minimal rust damage. However, getting down to the nitty-gritty and building a hot rod from the ground up will require a frame-off restoration.Doing a frame-off restoration represents a serious commitment of time and money. Many shops estimate an additional 200 to 400 work-hours to perform one. It involves removing the body from the car's frame (often, for the first time since the factory put them together) and then going over both with a fine-toothed comb. The process usually includes sandblasting, welding, and vigorous inspection before refinishing the frame with element-resistant primers, patching up any imperfections in the body, and rejoining the two in holy matrimony. Then it's time to worry about the rest of the car.Resto modResto-modding, a relatively recent trend in auto building, strikes a delicate balance between modernity and tradition. While not all hot rods are resto-mods, they certainly can be. Resto modding, a shortened form of restoration modification, is essentially about bringing an old car (such as a hot rod) up to modern standards technologically, all the while preserving its vintage charm.Resto-modding modifications can include virtually every system on a car. For instance, the safety equipment can be upgraded to include modern airbags. The brakes can be replaced with more efficient disc brakes. The fuel management systems can be updated to electronic fuel injection. These upgrades bring the car up to modern standards, while retaining some of the old-school charm.Hot rods can be resto-mods, but so can virtually any vintage car. Even rust buckets that seem beyond repair, like tri-five Chevies and Ford Model As and Model Ts (some of the original hot rods), have been transformed with the resto-modding treatment, yielding some truly inspiring results.Proponents of the genre argue that resto-modding is the best of both worlds in terms of convenience and comfort combined with old-school charm. However, not every hot rodder will agree. Some argue that old technology is part of the fun of bringing a hot rod to life. Additionally, resto-modding can be complex and expensive, and it may not be suitable for all vintage cars.