Air leaking sound
 

https://cimg4.ibsrv.net/gimg/www.rx8...2a14567f2e.jpg
I hear a hissing sound from right side of engine bay, i turn off AC and all air and still remains. I have a roughish idle sounds inconstant and high idle at first then it calms down. I have no CEL or nothing on dash except for TPMS light because i have aftermarket wheels and tyres.

I'd start the car let it idle and spray that area with some carb cleaner and see if idle raises. If so your looking at a vac leak.

There is a nipple on the intake manifold ( the black ribbed thing) on the under side, roughly below the thing you've circled. It's invisible from above, you have to feel for it. It goes to the VFAD system which is part of the stock intake. Feel around for it and make sure there is a hose on it. If you do not have the stock intake and this is disconnected, find a way to plug that nipple. It will mess with your idle and performance.

Good catch I always forget about that nipple. Had ms intake since I bought it so it's been capped and forgotten about lol