It is to late for that, i bought Playstation 4 a couple weeks back, i have always had a week spot for Playstation, even i have owned Xbox, Nintendo, Sega, i bought the first Xbox 360 but the fan was so loud and the controller was chewing batteries, so i sold it just after 2 weeks or so.
But i agree i have watch some videos of FM4 on youtube and the engine sound is much better than GT5 and GT6, but as i understand Forza also have flaws, so in the end, it all come down to what flaws we can or have to live with.
And after PD became aware of how big issue the sound is for us here on GTplanet and they are looking for hiring additional sound engineers, the future of Gran Turismo is looking promising.
I am very curious and excited about Project Cars, i really hope it will be a great racing game.
Also i wrote in a early post here that if they don't do someting about the sound in GT7 i won't buy it, but i have to admit that i maybe won't be able to keep that promise, Playstation without Gran Turismo feels kinda empty... yes they belong somehow together.