Any engine old and new can be modified....just depends on how much jack you want to spend....New motors have more electronic control but they can be hopped up (and very seriously I may add).

 

With my background, I'll wait until I have a bit more electronic test gear before doing anything serious with a newer machine.

Sure the chips and stuff that are out there will give you a lot more gitty-up, but I like to know why and how.

Also, fuel injection is a great way to go, but tailoring will also call for some expensive test equipment. At the very least, an oscilloscope.

And the one I want costs almost as much as the truck itself.
Then there are signal generators, etc...

Not yet, people. Not me.
At least, not until I get back home and reclaim my holy sanctuary: "The Garage"...

 

I am here to tell you from everyday driving experience about the difference in the 2. I have a 2001 Screw XLT 5.4 2wd 3.55 ls., a 97 f150 reg cab 5.4 auto 3.55 gears w/ls., and a 1999 and 2001 both Z71s with 5.3s, both w/ 3.73 gears w/ lockers. The 2 Z71s are company trucks. The lower rpm power, and the transmission shift points of the fords make them far superior. The chevy 5.3 will only give you the power you need for pulling a load or accelerating in traffic if you STAND on it. This is very aggrivating when pulling a trailer. When the the 5.3 shifts gears it looses too much power and takes a while to built up the rpms to get the power back. The tow/haul switch on the shifter is no help for this problem.The Ford 5.4 is smooth and strong through the gears when pulling a load or not. In a drag race between the 2 the chevy 5.3 has NEVER won because they bog when they shift gears. Not to mention small mechanical problems on the chevys like door glasses not rolling up, excessive tire wear, abs going out, door locks not working, engine rattle at start up, strange noises from rear suspension and hearing the dealer say "THEY ALL DO IT". There is no question to me who has the better engine.