Injectors are pointless. No cams or internals exist and if you have a 5 speed, nitrous will quickly destroy it too.
We are **** out of luck with out a m32 swap, forced induction or built internals.
Bottom line is this: the avg 1.8 owner does not care about mods. People who want to mod generally favor the 1.4. Leaving the 1.8 with less aftermarket. People who do mod the 1.8 have a hard enough time biting the bullet for a $600 header let alone a $4k turbo kit.
Everyone says they want one, but when it comes time to buy they back out, so from a business standpoint there is not point in selling a kit to a whole 6 people.