i honestly don't know what matt did to your car to make it run 13.0. He must have just not felt like tuning my car right.
I thought i would get a 3.4 when i put my xp cam in. I just can't see my car running a 3.4 properly as is. I'm going to try and make it next Friday (only if i have my car re-tuned, i don't want to embarrass myself again with my **** times)
Unless your car is extremely prone to knock I think you should be able to run a 3.4 just fine.