Lets just say the 2 are very different but if the drivers are equal, the 05' GT is faster than the SRT-4. I looked at both two weeks ago and ordered an 06' GT.
For the $26,500 I paid for the GT I could've bought an srt-4 with the stage 3 upgrades and been faster for the same $, but I think with stage 3 you lose all warranty. Speed wasn't the determining factor.
When it comes down to it no matter what you do the srt-4 is still a Neon. It may handle, accelerate, and stop better than any other Neon, but it is still a Neon. What a guy said earlier about not being able to "polish a turd" comes to mind. I also hate FF cars. I am not a Mustang nut, this is my first one. Honestly I only bought a Stang because there is no Camaro right now and I didn't want a rebadged Holden Monaro either.
Bottom line is the new GT is a better car than the srt-4. Especially when looks and build quality are important. No matter how fast an SRT-4 is I wouldn't really want one. If you find one that will outrun my 240SX we can talk.