What are the downsides to going 17x8 in the front for RPF1s (when the rears are 17x9) in terms of performance? If any
17x8 allows for possible upgrade to BBK later and it's staggered just like the OEM setup so wouldn't performance benefit go to the 17x8 F/17x9 R setup rather than a straight 17x9 square? Even though 17x9 has more grip in the front, I would imagine if you ran 255 all around the steering would feel really dull. Not to mention on a AP1, there might be oversteer.

17x9 looks better though I think.

 

Only downside is the 17x8 rpf1s are convex, while the 17x9s are flat faced.

 

Gotcha thanks. Would prefer flat look. If there's no real performance benefit to 8 in front I'll just go 9 square setup.

 

You got most of the benefits and downsides in your original post. 8 in front will also be easier to fit in the fenders, but I dislike the convex face to the concave face 9" wheels have. When I was non-staggered I didn't notice much increased oversteer while using 255 Dunlop Z2 tires vs staggered on Venus V12 tires.

 

You are going to need to do some work to fit the 17X9 on the front.