Noob question:

If I go with some stock JKU Rubi springs and a 2.5" TF BB on my 2 door X, will that lift more than the 2.5"?

 

Depends on the springs. I went from 14/56 to 18/58 and got roughly an inch added height.
Tons of info here...
https://www.jk-forum.com/forums/show...rings-Question

 

Most likely yes, it depends on what springs you have now, if you have a 2 door with soft springs and you get a set of springs that are stiffer form a 4 door you will get a small lift!

 

Yes. I got over an inch by putting 4 door rubi springs on my 2 door. Went from 14/55 to 18/59. I only have 1" coil spacers and plenty of room for 35" (33" in pic)

 

As mentioned above, it depends on the spring rates.

However, chances are that yes, you'll end up with 3.5" or even more. I don't know your finances, but if you're strapped for cash, I wouldn't add all that at once without knowing the outcome. 3.5"+ on a two door is going to leave you wanting track bars and front LCAs, and is likely to greatly accelerate the wear and tear on your driveshaft boots.

There's a reason you don't see a lot of "budget boosts" over 2.5".

Edit - Although come to think of it, I have heard of a handful of 2 door JKs coming from the factory with some of the highest spring rates. I would assume they could still safely install a 2.5" BB. So you may just end up with perhaps some flightier handling than you would have had had you kept your stock springs. I don't know . . . I'd be inclined to install the springs first (assuming the coil numbers indicate it would benefit you) and then decide whether to add the BB.