Having bought and traded a number of cars over the years (too many) I have discovered that what you see with KBB, NADA or any other source a consumer can use, the closest dealers come to the values indicated is fair to poor condition no matter how well you take care of the car.
The only exceptions are very high demand cars and even then it will be nearly impossible to get what is listed.
Dealers want to pay you wholesale auction pricing or jack up the price of the other vehicle. Generally when you hear what a great trade a person got, it usually means they paid more for the new one than they would have without a trade. Or they just have to get rid of the vehicle offered because it is costing them money to keep it.
In my case when I got my SRT6 almost two years ago it was a program car with under 600 miles that had been purchased at auction from Chrysler. The dealer had it 3 months and wanted to move it. I bought it for wholesale (at the time) $28K and they gave me $26K on my '04 Z4 2.5 which was KBB trade in value of good (the car was excellent). I told them they would have my car sold in 5 days and they did just that for $32K. For them it was a good deal. They claimed they broke even on the SRT but made $6K on the Z. They had no get ready costs and put it straight on the lot for sale.
That was not the norm. I knew my SRT6 would not have the same kind of resale, but I wasn't getting it for that reason. At this point I am not concerned with resale and intend to keep it as long as I can.
When I bought the Z I wanted to trade a '99 Cirrus that was loaded and in excellent condition. It had low miles and a low KBB trade in value of $7500. I had one offer of $3800 and another of $4000. I actually walked out of the first two dealerships disgusted at their lowball value. At the dealer I bought the Z from they offered $4K again BUT that one gave me a $5K discount off MSRP ($3K below invoice) on the Z (the best time to buy a roadster is in the winter).
If you want to sell and maximize the SRT6s value, sell it privately. Be prepared to wait, but you can point out how well you've taken care of it and all the mods you have made (dealers use the excuse that mods lower its value when they go to buy and emphasize their value when they sell)
Glad you decided to keep the SRT. You would definitely have missed it if you traded for an FJ. They are nice but they aren't a Crossfire.