I've read this stuff but it doesnt mean its 640x480, maybe for Namco high resolution is 320x480 instead of 512x480 or 640x480.
I belive in pSX debuf info (coz in other games is totally right) more than this lazy Namco text.
I dont see any other improvements than framerate. Except if you use the PS2/Emulator texture filtering like the capture
I do realize those notes do not actually confirm Ridge Racer Hi-Spec / Turbo Mode has 640 x 480 resolution.
However you are definitely wrong about the
only improvement being 60fps.
Whether the screen resolution is higher, or not (it
seems higher, though that does *not* mean it's all the way to 640 x 480) the actual graphics are most certainly improved beyond the first PS1 version that Namco made in 1994, which released in Japan in Dec '94 and in the west in Sept./ fall '95.
The textures, lighting and gouraud shading are significantly improved in Hi-Spec / Turbo Mode. The car models are just tweaked, though, and that aspect isn't much of a difference.
I own a copy of regular PS1 Ridge Racer (NA NTSC ver) and R4 Ridge Racer Type 4, with the bonus disc (NA/NTSC ver)
These (not my pics):
I have played them both quite a lot on my original NA / NTSC launch PlayStation, so I am not talking about emulation on a computer, or playing them on a PS2.
Just an original NA PS1 on a Sony Trinitron 27 inch XBR CRT and a 32 inch XBR² CRT. I used the S-Video on both.
The difference in actual graphics is not huge, but it's there.