I posted this on another thread but I think it may be applicable to a couple of your questions. I'm am sure not an expert like Gary or Wild One, and my full time racing experience is from the 60's and 70's but some basics still apply, I think.
I have a Vararam with the larger Moe's
throttle body. I'm happy with the results. Each bolt on mod you do is all a piece of the whole process. Each mod, singularly, is not going to reduce your track times by 5 or 6 seconds(exaggerated). Each mod, together with the other mod's you have done will become the "total package" so to speak and you will see a significant difference in the performance of your
truck because of
all the mod's together. It's pretty hard to measure each and every mod you do individually unless you have unlimited funds to dyno your truck after every mod. IMHO seat of the pants measurements has more to do with the amount of money you spent of a particular mod, instead of the effectiveness of that particular mod. The more you paid, the faster your
truck feels.
Jay