My sig tells my mods. I had 275's first since about 20,000 and still do with the Edg-Comp since aobut 25,000 I also have the Smarty. I have just replaced my stock clutch after 170,177 miles and a good fair amout of towing up to 23,000 lbs.
It is all in how you drive in my opinion. The 275's gave me about 1. 3 mpg gain and a nice little boost. The edge gave me good manuvering power and the smarty does a real nice job with the low end grunt off the line.
I do not use the Smarty during towing nor do I turn on the Edge for towing. The power is nice, but very easy to abuse and also sucks down my wallet for fuel. My mods give me good manuvering power when on the highway and daily driving with occasional fun using the right foot.
I would install the 275's first and see how you like it. Then move to the Smarty. This of course assumes you are running guages as your very first required mod.
Research long and hard, determine your style of driving honestly, pick your mods with an eye to reliability and economey and you will be happy with your choice.
I have all the power I can use, plus some, still runnin my original factory VP-44 with no signs of dying. Just ordered LarryB's contacts for the starter tonight.
Reliability is what you want. Good luck and have fun with your choices.
