What are your end goals for the car...just making raw power? The X is very capable of making huge power, just like the 4g63 did. It's only real disadvantage is it's weight if you are talking 1/4 mile stuff. I still fully intend to get my X down the 1/4 track quickly, but I had to spend more money then i would've liked
I would half way be tempted to suggest the 9 for straight 1/4 with a 5 speed. But the prices are almost too close, so if you can afford it, i'd probably say just get the X.