They in fact had to use new molds to form the upper bumper plate supports as they are shorter. The entire design of the car was based around achieving the lowest possible CG, and this included the bumper, so sometimes there are sacrifices that a designer must make to acheive a certain goal. Having said that, this "problem" you refer to is so minor, it leads me to believe(and everyone else apparently)that you will never be happy. I suggest you purchase the T3 bumper supports, foam bumper and be done with it.
Latest report on the T4:
This past weekend Andrew and I were racing again(fall fiasco at Lou's speedway) and it gave us the chance to try the setup we ended up with from IIC. Out of the gate the car was decent but was not quite as good from the first test day a week prior so I decided to go back to the original setup I had built the kit with. To my surprise the car was much worse.
Since we were now qualifying, I decided to go back to the IIC setup including a couple other changes I thought would help. Turns out, it did! For the main, I made one last change(thinner rear diff oil) and the car was noticeably better and as reported by Andrew, much easier to drive.
The key things I learned that day were:
-Setup works very well on two COMPLETELY different tracks. Something we couldn't do with the T3. Of course, minor changes might be needed(more for feel than anything).
-Anything lower than the second hole from the top on the rear shock tower is less than ideal(IMO). I think this might have something to do with the rear springs being progressive and as we all know, laying the rear shock down does the same thing. Perhaps with linear spring sets I will be able to make it work.
-Short rear link does not provide as much grip as the T3. Also, might be due to the progressive rear springs. The next test session I will try it again with less rear camber.
Hope this helps some of you.
Corey