Ok, I have just read the other posts. I see where others are coming from, and I have re read your OP.
I think everybody is confused like I am/was. Normally you would have a goal to slam it for aesthetics (car shows etc etc) or
Have a handling focus for track work.
While you can use coils for stance and bags for track work neither is better than for its original
I don't know the coils you have mentioned, Sparoz does and if
He does they are obviously good cos that guy burns money on expensive shit lol.
At the end of the day if you want to enter you're car in time attack go nuts, buy the best coils you can but be prepared to pour a whole lot of other Coin into other mods ( I actually would hate to see what it would come to)
If you want to stance it for car shows/aesthetics buy the bags.
Or buy cheaper well know coils for a quarter of the price of both. The well known coils aren't shit at all. The KW V2/V3 they will out perform your driving ability guaranteed.