My KA24DE has 165K miles plus...
 

Is it worth getting Headers, Intake, Pulleys all that good stuff?

How long do these engines usually last for?

KA's usually last a LONG time. If the engine is good or if it goes and you plan to replace it go for the mods. If you ever plan to go SR I say save your money.

You should get plenty more out of it. Drive it until it breaks. Then SR. Sell whatever parts survive when you are done.

I will buy some. :)

I love picking up cheap parts.

I recommend buying seafoam and clean out your internals.