So I did some looking around regarding some hard evidence as to the benefit of a shaved throttle body and it turns out that it's pretty substantial.

On an LS1 (78mm TB) a shaved throttle body is worth about 7 RWP.
SHAVED LS1 TB DYNO by zimbu themonkey, on Flickr

link to full article https://www.cartechbooks.com/techtips/ls-dyno

I also found an interesting link to a company that specializes in shaftless throttle bodies and they claim that it's worth up to an extra 7% worth of airflow
SHAFTLESS THROTTLE BODY by zimbu themonkey, on Flickr

Link to companyhttps://www.atpower.com/products/dbw-throttle

I have an extra throttle body kicking around and what I think I'm going to try is cutting the top half of the shaft off altogether. From there, I'll shave the bottom half as thin as i can and knife edge the leading and trailing ends of the plate. Then, all you do is run the screws in with some red Loctite and shave the ends off a best as you can.

I measured the thickness of the shaft and it's 10mm. When you eliminate the top part of the shaft and shave half the bottom shaft, you're taking about 5-6 mm out of the way of the fastest part of your airflow.

So there you all go boys and girls, looks like we have a free DIY way to make another 7-10 CHP (at least on a 4.2 V8).

I should add that this ought to work as good or even better on a forced induction engine as pulse resonance tuning benefits are actually magnified in a compressed air environment.

So how would you explain the results on the LS1 engine? Do you think it was that restricted then?

The airflow (as represented by HP) is similar to what a modified 4.2 would flow (a little higher, but in the same ballpark) and the TB diameter is close as well (78mm vs 80mm).

The other consideration is that the removal to flow restriction is placed in the highest flowing portion of the air pulses. Bearing in mind that flow rates for fluids are slowest at the boundary layer and become faster closer to the center.

While results may vary with modifications, the comparative ease and low/no cost of shaving the throttle blade make it a no brainer IMO.

The intake manifold to head porting is also horrible from the factory. I opened one 4.2 intake once and ported it. Never dynoed it afterwards though and not really sure if it did any good. The point being anyway, throttle body is a bitch to remove with manifold in place. It's actually a lot easier to lift the whole manifold with the throttle body out of the car and at that point You might as well go all the way and dremel the intake runners.

At least with the old C5 manifolds that are magnesium alloy. B6/B7 4.2 manifolds are plastic if I remember correctly.

1st post, but isn't it difficult to compare forced vs. n/a, where air velocity is more important for cylinder fill? I know from n/a experience that a properly ported runner with a higher floor and higher velocity can make "better" power (area under the curve) than a larger, direct shot. Perhaps this nominally sized, "shaved" TB allows better fill vs. simply increasing it's size, which lowers velocity? Please school me if I'm off-base, lol...

I've been thinking along those same lines actually.

Bear in mind that in any tube, the column of fluid flows fastest towards the center with the edge (boundary layer) flowing 0. Imagine putting a stack of paper on a table, extending your fingers and pushing into the stack. 

The way I've conceptualized it is that what I'm doing is eliminating a restriction in the fastest flowing region of the intake charge. With this being the case, I could see this modification freeing up more 'momentum' (for lack of a better term) for the incoming pulses.

Put another way, adding 'momentum' to the air pulses and presumably increasing velocity, would be akin to the ram tuning effects that you get from manifold resonance.

That said, it's completely speculative on my part. Maybe we're completely off base and it won't make any difference at all.

Only one way to find out though