According to Dr. J, 30 to 40HP is a reasonable expectation for the 215's. When I installed mine, I was running a TST #8 plate and the difference was very noticeable. I have no problem supporting Joe's numbers.
On EGT's, my experiance has been that everything that improves performance, raises the EGT's.
With the #8, plus the 215's, pulling my backhoe (combined weight for JD 310 and 3 axel trailer is 20K, plus truck = 27000GVCW) I could see 1300deg's if I stayed in the fuel in 4th on about anykind of grade. When pulling about 5000 lbs. in the Rockies at 8000 feet, I could produce 1400 at will, however, just back out of the fuel a bit and everything would get better.
I pulled the hoe to and from Hot Springs Ar. last week with the #5 plate in place, and I can now generate 1400 plus at will on the bigger hills, however, it's a simple thing to watch the EGT gauge, and using the old right foot, keep things under control.
As you can see from my sig. , there are several things that would help me keep EGT's under controll. 4" exhaust (or stacks), 16cm turbo housing, are at the top of the list. I have tapped into the cowling duct with a 4. 5" hole and ducted air to the stock air box. This helped slow the rate of EGT increase.
Although I seem to be painting a picture that is negative for increasing fuel for power, that's not my intent. While I can't just put the petal to the metal and let her eat, the additional power my truck has is well worth the small inconvience of montoring the EGT gauge.
A friend has a Pete with a big Cat engine, he also has to watch EGT, said he tries to keep it below 1200. Watching the gauge is a small price for the additional power IMHO.
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"95" 3500, 4WHD, 5 spd, 4. 10 LSD, Rancho 9000's PacBrake, Isspro EGT, 50lb. boost, TST #5, AFC kit 215HP injectors,no cat, muff