A 1.6k Superlight is ideal for Class 2 or 3, the only difference being tyres. List 1A for class 2 (typically Yoko A539s) and List 1B for class 3 (typically Avon ZZS). Please don't start upgrading the engine just yet... the biggest factor by far is driver ability/confidence/experience, followed by tyres/setup. An extra 15 bhp could be expensive, and you won't be gaining many 10ths. Accurate cam timing with verniers and a 52mm TB may be worthwhile if you really want to tinker before you start. Class 2 was very quiet in 2022, following an exodus up to a busy class 3. I suspect that might continue in 2023, so you might want to watch the entry numbers. Its always good to be in a bigger class with plenty of competition throughout, and after many years in class 2 on wooden tyres, I'm enjoying the extra grip on track and road with ZZS. Not quite enough grip, but thats another story. Flat flooring is usual, but if you are already confident with your car setup, I suggest you leave well alone for now. If the speed bug bites, there will be plenty of advice on ways to spend your cash, but I'd run with what you have for a first season. Its always good to have some excuses up your sleeve as well, just in case you don't win.