What improvements did you expect with the TPI, and what improvements did you actually get?
What's an improvement to me might not be to someone else, but I set out on this project with some goals:
-Use regular fuel injectors that are low cost and easy to get. The refurbished and flow matched Bosch 3's in my truck were $200.
-Keep it serviceable with OEM consumables. TPI needs a box of o-rings and a box of gaskets, otherwise it's any other old school sbc intake.
-Simplify the system in the ways GM never could. No AIR, no EGR, no cat, no TV cable, no wacky sideways distributor cap, three less o2 sensors. Most of those decisions were made based on what my ECM supports, but it's essentially a minimally complex system to support batch fire multiport fuel injection.
-Have a modern ECM that's easy to update with the changes I make to the truck. Gear ratios, tire size, camshaft, shift points, rev limiter, boost, whatever I want. Datalogging at the push of a button.
-Take advantage of the long runners for maximum torque output at towing and hauling rpms (the wave tuning effect happens between 2500-3800 rpm).
And I did get all of those things. I don't need a fast truck but it hauls out well. I skipped installing a cam because I found the bearings in the oil pan but honestly now that I'm driving it, it's totally fine and absolutely traction limited with an open diff. Running the throttle off the cruise control peg (not recommended) makes it easy to crack the throttle kinda fast and I'm still chirping it around corners like a goon unintentionally.