Ill say go with the RB20. Youll save money in the long run. Because by the time you get it installed and refreshed with new gaskets/timing belt/water pump, you still havent spent as much as you would for an SR/RB25. And you play with the wiring about as much as you would with an SR anyhow. RB25 is where the wiring gets tricky. Youll bang the firewall for any RB.

If you go RB25....do it with an RB20 trans. Sure, they are weaker, but you can use the stock S13 driveshaft with it that way, instead of having to buy a custom made one.

Personally, both have their pros and cons. 25 is more power out of the box, but costs as much as an SR(makes more power than an SR which is why I cant understand why people still do the SR, but thats neither here nor there). 20 is as much power as an SR, but costs far less. Means more money for mods(compressor/fuel upgrades).

I gave up my RB25 project to go KA-t. After spending around $1200-1500 in parts, Im starting to wonder if it would just be better off to go RB20 like I wanted to in the first place(even before I went RB25). KA-t is nice, and I am glad that guys want to give the engine some love. But an engine that was turbo to begin with seems like a better starting point to me.

And no, Im not speaking out of my ass. Ive actually done an RB20 and an RB25 swap.