lot's of questions
 

i'm going to go straight pipe but was wondering if i should put in 4'' or 4 1/2'' pipe, or should i stay 3 1/2'' pipe does it make a big difference. my goal is to spend a little bit of money trying to make some mods so that i get better mpg's and eliminate performance restrictions that factory does to meet emission control. i was reading a post and the few things that interested me was putting is banjo bolts, fpg, sct with custom tunes and my big question is egr delete kit. is that a must because i read 1 post that said to change coolant filter and put in non silicant coolant and you should be fine. thanks for any advise i get!

Most of the delete pipes you buy are 4", but reduced to 3 1/2" on both ends to accept the stock piping. It wont make a difference how big you go since the rest of the system is 3 1/2, so that's the restriction. If you get an SCT, you will want multiple gauges, but FPG is the most important, and pyro would be next if running hot tunes. EGR delete is a great idea. With the cooler or valve in there, they always have a chance of failing. I would do an EGR delete and a coolant filter setup. Coolant filter setups are one of the best mods and one of the least expensive for our trucks. They should come from the factory with them. The filter will catch some of the silicates in coolant yes, but the block itself loses sand deposits, since they are sand-cast from the factory. The filter prevents the crap from clogging the oil cooler. The oil cooler is there to keep the coolant and oil temps close to each other. This is why I recommend oil temp and coolant temp gauges, you can see when that is starting to clog because temps will start to vary radically. This leads to blown EGR coolers and headgaskets failing.

just wondering about the banjo bolts? are they a good idea even as stock as my truck is?

Yes, they are cheap, and they will certainly not hurt anything. I had the three hole jobs from ebay on mine for a while. You can get those, or go to your Ford dealer and get the 6.4 bolts. I think the three hole ones from ebay had larger passages over-all, despite the 6.4 bolts having 4 holes. Most of the fuel systems I see on trucks I laugh at because they're totally unecessary. I'd just do an Airdog 2 and those bolts and call it good. However the only way to truly know if you need more is a fuel pressure gauge.