I, too, am about to try some GTX 5w20 in my 2.3. You must be referring to the AAP deal going right now. Good deal especially with the purolator.
Right now Im using PYB. Just a hint of cold startup chatter. At operating temp, one of the quieter oils I've used.
Before this, I had M1 0w20. No cold startup chatter at all, but it was louder once at operating temp.
Im looking forward to trying the GTX. I think its the thickest 20 weight available.
Im trying out every 20 weight I can easily get my hands on.