I will be the first to admit it: I took an immense risk buying someone else's modified car. I drove 550 miles to Utah to buy a Toyota MR2, with only a handful of pictures on the internet and a list of parts showing what had been done to the car. I was lucky to have bought from a responsible owner with high standards for workmanship, and proper supporting modifications for some of the changes made.
Not everyone is as lucky, however. YouTube channel Deutsche Auto Parts has uploaded a video on an inspection they ran on an extensively modified Volkswagen Golf GTi VR6, one that should have been inspected before purchase, as some signs of poor maintenance and low quality workmanship have manifested themselves.
The first point the YouTubers emphasize is the value of a professional pre-purchase inspection. This is true of all used cars, but doubly so for modified cars, as many aftermarket parts put additional stress on the components around them, accelerating wear. Furthermore, you don't truly know how the previous owner maintained the car. Did they jump it over curbs at every opportunity, or read the owner's manual with the focus of a double dose of Adderall? Poor maintenance can be a bargaining chip to lower the price of a modified car, provided the owner realizes what they have overlooked.
Since the buyer did not take the GTi in for a pre-purchase inspection, it instead received a post-purchase examination, which likely instilled a sense of buyer's regret. A slew of issues were discovered in the inspection on several areas of the car. Worn control arm bushings were found during the test drive prior to lifting the car, and once the bumper was removed, overspray indicative of a front end accident repair was found. The condenser core support and the A/C condenser showed visible signs of damage—the support was cracked and the condenser bent—suggesting the repair from the suspected front end crash had been completed without care.
With how much this Golf was lowered, it would be a surprise to see all of the installation done in the proper fashion, and this car was no surprise in that department. The frame had been notched to permit axle clearance, but the frame had not been reinforced to compensate for this clearance. The sway bar was sawed off without care as to how the vehicle handled. A fuel line had been damaged when the car was lifted by a numpty and then repaired by an equal buffoon, who, rather than buying a new fuel line to rectify their mistake, repaired it on the cheap.
While this is a model-specific guide, the video's points hold true for modified cars in general. Mechanical problems and shoddy workmanship may not be known to the seller, and it's the purchasing party's duty to remember these two wise words: Buyer beware.