My proverbial two cents' worth, here goes. When this thread really got going, I turned up fuel on my 8.3 (M931A2, 14.00R20 tires) using all the recommendations from neverenufhp, and installed 4K GSK. I adjusted the fuel rates several different times, and while I got puffs of black smoke consistently, EGTs would quickly rise anytime I was trying to pull a heavy load uphill. Flat ground performance increased significantly from stock, and on the hills it was a bit better; I just had to watch the EGTs and downshift to keep from damaging anything. I cleaned my stock air filter, and the intake stack cap was flowing air in spite of the obvious heavy paint coats (no holes plugged, could feel air flowing into/through cap). But I just wasn't happy with the setup and planned on putting everything back to stock just to not have to worry about the quickly-spiking EGTs. In spite of adjustment after adjustment, I just could never seem to get things right (and I've read this thread thoroughly from start to finish many many times to be clear on what I was doing).
After my exhaust manifold gasket blew out on cylinders #1 & #2, I purchased the aftermarket intake air filter from TMG along with an air ram intake cap (what the heck, at least it wasn't painted over). After everything was back together, but before turning the IP back down to stock levels, I had to do some test runs to ensure that the new exhaust manifold gaskets were OK and that there were no coolant leaks. As soon as I fired up the truck, HOLY MOLEY there was black smoke everywhere! And tons of soot blew out of the muffler/exhaust, all over everything I had outside.
Long story short, I ended up turning my IP back down to stock settings, and it runs just how I want it to...takes the hills much better than before, the EGTs are slow to rise on hills and I typically take the same hills one gear higher now. My engine was simply starved for air, not fuel...
I took a test trip to southern Utah and back, loaded both ways (10K-lbs northbound, 12.5K-lbs southbound, on I-15). With fuel setting set back to stock levels and the new aftermarket air filter/air ram intake, the differences were dramatic! Now I had LOTS of top-end power; once everything spooled up to around 1800 rpms, the truck was ready to run and EGTs actually dropped! It was all too happy running around 2100-rpm at 60-62mph, even up 1% & 1.5% grades on hills. Hills up to 3% to 3.5% I eventually had to downshift to 4th gear as EGTs gradually approached 1250 (my threshold). On one 5% hill I had to downshift to 3rd gear, but it kept revving around 1900 and EGTs were barely into the 1100s (a dramatic improvement from before I switched air filters).
On the return trip southbound, I had a nasty headwind the entire way (25-30mph steady). I thought for sure that it would take me forever, as it would have before the air filter/IP mods. Nope, the engine performed as before, and the headwinds only added 50-100 degrees to EGTs. I was able to do 60-62mph consistently, even up 1% to 1.5% grades. The engine is really responsive above 1700rpms, and headwinds/hills are no longer a challenge. The difference was dramatic, I was truly amazed.
So now my next upgrades will be focused on increasing & cooling air flow into the engine: air-to-air aftercooling, etc... I will be closely following other members' progress in posts above, and already have a radiator with built-in ATAAC new in the crate....just have to sell this house first so I hope in late summer I can start with the radiator swap & ATAAC install.
