skazz - I also have AC on my PC. Try and compare the two. I find it's heavy on the PS4 but not on the PC.
I've posted on another forum so I'll cut and paste my findings (and I've tweaked my setttings too)..........
(please correct me if I'm wrong).
I found my T500RS on PS4 very heavy with a lot of resistance, and lowering it to 20FFB makes it a lot better, but I found it's still too heavy if you drive with traction control 'off' and therefore have to oversteer your slides, then 10>15 FFB is better depending on your car, but then you lose some of the feedback feel of tyres slipping, road feel, etc.
I also have the PC version, (poor GPU so PS4 graphics are better for me), and I compared the 2 versions. What I think is going on is the T500 drivers on the PS4 are set up poorly. With PC we have an overall gain FFB strength in the control panel, and it's often recommended for most games, including AC, to use 60%, then set other FFB 'in game'. But The PS4 setting is a lot stronger, with far more resistance for all games (I also have dirt rally, pcars, f1 2016 on both PC and PS4). For me to get the same strength on PC I have to run that overall gain over 100% (possibly 150%). But that's not all. On PC we tend to run with no spring and no damper settings (even though you can run up to 100% on both). If I select both of these as 100% on PC then, and only then, do I get the same sort of heavy feeling that the PS4 version gets. So in summary, I think it could be a Thrustmaster driver issue and they need to have the spring and damper 'off' as default, so the wheel isn't feeling heavy. My brother has a T300 and I can tell you that he doesn't get the heavy resistance when trying to catch slides.
For info I run FFB (low main FFB strength but more roadfeel to compensate for the lower FFB ) as:
ffb 12%
curb 10%
road 70%
slip 20%
understeer off (currently experimenting with on)
Tested on road cars, race cars and my favourite Ferrari 458 GT2.
Oh and I also have the latest firmware, - version 43 Package 2016_TTRS_1