Comments on these components

Amp Kicker 65W x 4 /400 x1
Kicker 8" 4 ohm sub.
Rockford Fosgate HPC-2205 5.25" 2 way for the rear. (Will these fit in the back OEM wholes)

Rockford Fosgate FNX2514 5.25" Component speakers. ( Will these fit in the fron door panels?

Where should I put the sub?

My car is 330CI 2203

I had the RF Fanatic X components in my Eclipse and they were/are awesome. They use a silk dome tweeter and never sounded harsh just crisp and clean, non fatiguing like some metal domes can be.

If I were you I would go with the 6.5" (6 3/4" more or less) as you will get much better midbass output. The X series come in a "U" universal 6" size and the 6.5" (6.75") size. The larger size fits in a 6.5 hole but the driver is slightly bigger in the basket.

Also, I had a 10" sub in my coupe and that is the best size for deep punchy bass that's not overbearing, in a coupe. The 8" may not give you the depth you will want.

I used a Q-logic "sealed" type box. I think they make great sub boxes and the price is great for the quality. Remember to buy "poly-fill" and lightly stuff the sub box before mounting in the sub. The polyfill will add depth to the sound as it makes the speaker think it's in a larger environment. It adds to the accuracy of the sub bass tones as well. You can buy the poly fill at a crafts story. It's the same stuff that's used to stuff pillows.

As far as placement try it in a few locations to see if it makes a difference.
I had my sub placed towards the rear of the trunk area mounted inside the cargo net which held it perfectly and the sub was facing the front of the car.
Awesome depth and tone. If you don't have a net to hold the box, then you can use velcro. Attach the grab side to the bottom of the box. It will attach the carpeted side of the floor matt on it's own. Use long enough strips to go all around the bottom of the box and that should hold it securely. Velcro has some great holding power.

TT