An upgraded filter will do absolutely nothing. No performance gains. No extra power, no throttle response, nothing. Barely any audible difference (a clean OE Mann/Bosch/etc filter will probably do more). Absolute waste of money - it will simply make no difference on a stock car, or even a car at stage 1, 2 or 3. An upgraded intake will also do nothing for performance (unless you're tuned enough to need it - my guess is less than five cars on this entire forum fit this category). That being said, a cold air intake will sound much better - although you want something that is a duct design (like the Racingline R600 or Forge example) rather than an open cone design. The latter severely increases the risk of water and/or crap ingress into the turbo. The only restrictive part in the stock system is the elbow. If you're going above stage 2 equivalent, you'll want to change this out. I know someone with north of 500bhp in a vRS230 that is running the stock air box and intake pipe, with an upgraded elbow. Likewise for the turbo muffler delete - absolutely pointless in irrelevant, unless you're running a built hybrid turbo G82 with 1000bhp (which would probably benefit from an upgraded air filter, to go with it's monsterous open cone intakes). Sorry to say, but all this talk of increased air and fuel flow is rubbish. The EA888 isn't really a performance engine. Even in an RS6, changing the air intake has no bearing on air flow. There are so many additional factors at play. If you were to hybrid turbo the car, after doing a downpipe, catback and the rest of the mods, I still doubt you'd need to do anything to the fuel system beside putting in a Golf R fuel pump. Similarly, you do not need to be thinking about which petrol to put in your car. An Octavia vRS is't a performance car. If it is, then it is at the absolute rock bottom (for the record, a performance car is something that begins with M or RS, or has AMG, Ferrari or McLaren in the name). The difference between '95' and '99' fuels (and others) are a few things. Firstly, the more premium fuels have a higher octane. This makes no difference unless you are driving a 488 Pista, or a heavily tuned car. It is true that your car may run a little better (higher mpg, etc), but this is only true because a given amount of fuel has more 'go' in it - it's a moot point, as the more effective fuel, is more expensive. This difference is also quoted to be around 2%. Not worth it. The second difference is the (bio)ethanol content - E5 vs E10. E10 is the cheaper stuff, and contains, you guessed it, 10% of bioethanol. This stuff isn't the kindest to seals, hoses, etc, but unless you're driving a Mk1 GTI, you should be absolutely fine. The nicer fuels tend to have up to 5% of bioethanol in them (sometimes none), which makes them older car friendly. Finally, the premium fuels also contain additives and cleaning agents that help keep things running smoothly. This is the only real advantage of using premium fuels and, even then, can likely be achieved by using a bit of 99 once every few fill-ups. Stick an OE air filter in the car and spend the difference on half a tank of 99. Job done. P.S. @JohnMack an Octavia vRS Challenge is a standard Octavia with lots of options stock. IIRC, for the 2019MY, this included stuff like front sensors, ACC, electrically adjustable memory seats, folding mirrors, Canton Sound (?) and some alcantara seats, among other bits. Weirdly, it didn't include the digi dash. There is no mechanical difference from a vRS 245 which is, of course, a GTI PP underneath.