Billy, correct me if I'm wrong but the 'crate engine's' usually are in the low-mid 3,000 dollar range but only get you less power by roughly 40rwhp or so.
The TFS kits give in the 300rwhp range, and the gt40 crate (if that is what you are referring too) get around 250rwhp or so from what I recall...
Do the install yourself and save $1000 bucks, it is actually pretty easy
I've seen the gt40x crate engine on the chasis dyno. about 270rwhp, with a better cam, and the heads cleaned up a bit (valve job, no port work) it will goto 300rwhp.
I've seen it with the E cam, make 316rwhp and run 11.87.
The problem is that X heads are very inconsistant, the production seat pressure and valve jobs range from decent to horrific, it's a crapshoot.