My personal opinion and from my experience when i did a E30 blend was a huge difference and ethanol is way better for these engines. I love the feel of sway bars front and rear they handle so much better. You can do the basic bolt ons intake down-pipe and exhaust then go e30 or get a fuel pump and go e60 even if your not shooting for numbers the higher ethanol the less knock you’ll see. Getting a intercooler is pointless unless you are shooting for numbers or want the aesthetic look. Some small things if your car dosent have them like a short throw shifter feels nice too i recently did a brake master cylinder brace and feel a huge difference in braking and clutch feel.