Does a tuned or modified WRX need more frequent maintenance?

Yes, though the change is one of attentiveness rather than a fundamentally different service schedule. A tuned FA24 runs higher boost, higher cylinder pressure and higher sustained temperatures than a stock one. Nothing about that requires exotic maintenance. It does mean the consumables wear faster and the margin for ignoring something is smaller. **Oil, more often.** This is the big one. Roughly halve the factory interval - around 3,000 miles rather than 6,000 for a tuned car. Oil is the cheapest component in the engine and the one doing the most work under boost. **Spark plugs as a wear item.** Higher cylinder pressure makes a marginal plug misfire under load, and on a tuned car a misfire is not just a rough running complaint - it looks like knock in a datalog and it can genuinely damage things. Plan on replacing them meaningfully sooner than the factory interval suggests, and always before a tuning session if the car has miles on it. **Fuel quality, consistently.** A tuned car is far more sensitive to fuel than a stock one, because the map assumes a specific octane. Using top tier fuel at the octane your map expects stops being a preference and becomes part of the maintenance regime. **Actual monitoring.** This is the real difference between owners who keep their engines and owners who do not. Watch knock behaviour, watch oil temperature, and pay attention when something changes. A stock car will usually tolerate being ignored. A tuned car gives you warning signs and expects you to read them. **Check for leaks periodically.** Boost leaks develop at couplers and clamps, and on a modified intake tract there are more of both. A leak that appears under boost is invisible at idle and shows up as a car that quietly makes less than it should. What does not change much: coolant, brake fluid on a street car, differential and transmission fluid on a manual driven normally. These follow their normal schedules. On a tuned automatic, transmission fluid is the exception and deserves a shorter interval, because the gearbox is absorbing meaningfully more torque than it was designed around. The honest summary: budget an extra oil change or two a year, a set of plugs sooner than you expected, and the habit of looking at your own datalogs occasionally. That is genuinely the whole list. People who describe tuned cars as maintenance nightmares are usually describing cars that were modified badly or ignored, not cars that were tuned well and looked after.