is it worth it to buy the WRX because the RS cant handle a turbo because it would crack the headers? or would it be worth it to buy the RS and just do an STl or WRX swap?

wrx
more power and a lot of aftermarket parts

l do not think u realize how much it will cost to do the swap properly. Even if u can do the work ur self, it is about 3000 to 5000 dollars for all the parts including the wiring & re wiring the car is no easy task. If u r wanting the power of a WRX then get a WRX. If u get one that was well maintained, it will just be more reliable that way. If u shop around on NASIOC or RS25.com, u may find some one selling an already swapped RS. Worth a look if u really like the older body style. They were lighter.

Buying a WRX is cheaper than buying an RS and doing the swap.

Go with the WRX. The cost, time & complexity of the upgrades just r not worth the trouble.

I've had both a 2.5RS & a WRX, & miss the smooth torque delivery of the stock 2.5. You've got to keep the WRX on 3000 rpm to spool the turbo & have any power. l guess u would not be satisfied with one of the last 2 door 2.5RS models, a good exhaust & intake setup, a new chip & some sticky tires. l would. Probably be more fun to drive than my WRX ( l am not complaining, it is great, just more turbo lag than l like).