what do u think?

I would say keep yours. The fox is nice and has super low miles but it is still a 23 year old car and will feel like one.... I mean if your looking for more speed it's easily achievable with yours... other then having something different I don't see it practical getting rid of a perfectly good car for a car that could have been molested by the previous owner. :shrug:
 
^^ I think he may have been talking to Mike..

I think they are both nice cars... Like said before, I would just go with your feeling.
It all depends on what you want in a a Mustang. The fox will feel completely different from your car. It could be good, could be bad, thats up to you.

Although, If I had to pick between those two cars, I would go with yours... hands down.
Part of modding cars is getting to your goal by yourself. Building your own car comes with a sense of security, that you know whats been done/how it's been treated etc... and buying a car already built lacks that security. Who knows whats in store for the future.
It could be a really good car, it could be bad.
If you end up trading, have a performance shop look at it, or if you can, do it before any transaction.

^^ MY .02 :)

Good luck!