I had a couple of "tuned" car way back when that would beat cars with twice the money wrapped up in them.
My secret? Well, it's just us, right? Several quick oil changes with filter to flush the motor, new spark plugs, fuel and air filters, clean the air flow meter, throttle body and AAC valve, set the timing and tighten the throttle cable, and flush the intercooler and radiator fins of years of accumulated crud.
When I was seriously street racing most all my cars had nothing more than a full exhaust and high flow air filter, a piggy back fuel computer to get the most out of the OEM fuel system, a boost controller set to a reasonable level and a boost gauge. So many "tuned" cars lost to a car with a simple tune up, it was ridiculous.
"tuners" pfft, Throwing a bunch of random parts at your car isn't tuning and that crap only impresses when hard parked. If I wanted to park and show off I would have drove a VIP car here. This Skyline's for racing. You can tell by the lights.