<center><img src="http://pictureposter.audiworld.com/25140/throttle_body2.jpg"></center><p>I lost a looker, but I think I gained at least 30 CFM. What do you think?

maybe it's just the lighting, but I think the roughening should be done completely random until no linear or circular (etc) pattern is visible.

as it was really gorgeous. One last thing you may wanna do is an inside bevel around the flange inlet on the inside... make it about 1/3 it's original thickness with a taper that extends about 1/4" inside the flange all the way around.

I've given up guessing CFM gained with anything as the more I learn the less accurate my guessing becomes. But you're definately ahead of where you were.

A picture can be worth a thousand words.

As for the glitz, I still have the photos, and, besides, I cannot see the inside of the TB when it's on the car anyway. However, I can feel the improvement on the butt dyno everytime I depress the accelerator pedal.

I have said it before, and I will say it many times over again--engineering is the science of compromise (kinda like marriage).

<center><img src="http://pictureposter.audiworld.com/711/rtbrev2.1.jpg"></center><p>
As you can see from the pic the edge thickness around the secondary flange inlet is lots thinner. Keeps air from hitting it and bouncing/scattering all over the place. Makes for a smooth transition of air into the TB. From the 9 o:clock-to-3 o'clock position clock-wise circumferentailly around the inside of the secondary ventury how the taper is shaped and that the shadow would indicate approx 1/4" depth of bevel.

Later, on this RTB the primary venturi was given the same treatment. It's a lot easier on the XTB's (and yours) due to no internal velocity stack that extends to the same height as the flange inlet.

I have only test driven the car for a few miles since putting it back together, because I spent most of the day on my car doing preventative maintenance/cleaning and redoing the TB, and my dinner guests came to pick us up and I had not even taken a shower yet.

However, on that short test drive, I did a few semi-hard accelerations once the car warmed up and it appeared to gain some power on the top end as the tach really seemed to move quickly between 3000-5000 RPM.

Thus, a tentative "YES", I felt a difference. I will get to do a really good test drive when I drive 500 miles (much of that on desert and rural highways) on a business trip on Tuesday.

<center><img src="http://pictureposter.audiworld.com/711/rtbrev2.3.jpg"></center><p>here's a shot after the primary side was finished. Whats hard to see in this pic is that the "thicker appearing" flange wall between the primary/secondary side is actually tapered as well. But since epoxy is built up to the top of the flange and shaped for flow it appears to be flat rather than actually contoured and radius-blended into the epoxy.

I cant wait to do the shaft contouring and check flow results like this RTB when I do my own personal XTB with another special TB core.