I have a remapped GT 3.2 and a 2.4 159 Ti SW, it's pretty special when I go for a spin in the GT, but honestly the 2.4 is a great machine and I've not had anything done to the engine yet. There's enough power as it is that I don't yearn for the GT's power. The noise is totally tractor like on start up and for a few minutes after, but otherwise it can be a low noise cruiser. I couldn't have a 3.2 159 because I didn't want 2 cars in the highest tax band, fancied a 1750 because of the power, but apparently no way to make the sound justify the power, never actually tested one though, out of budget for me with a TI spec.
I can't say you'd be unhappy with amy of the 159 engines, because I've only experience of the 1.9 and 2.4, but the 2.4 SW would almost tick all your boxes and it looks seriously good. GTA SW is a very good looking car though, I love em.
GT 3.2 V6 - Q2, KONI FSD & EIBACH PROKIT, GTA REMAP, MICHELLIN PS3's, BMC CDA
159 SW 2.4JTDM TI - ALFATUNED, WIZARD BACK BOXES, KW V3 COILOVERS, NOKIAN WR A3/MICHELLIN PS3, PCA DYNAMICS ALIGNMENT.