Can I get a 18t turbo with a speed tunning chip and maybe some bigger injectors and be ok?
Sure. Don’t do the 18t until you get a tune and do some exhaust upgrades, though. The tune is the important part – too much boost too low in the rev range, and you get bent rods.
Again, keep in mind that with going to a bigger turbo, you’re going to lose some of that get-up-and go off the line. The S70’s acceleration/tall first gear make it useless for trying to dart out in traffic quickly, but great for passing power from 30 mph on up.