I've searched high and low but could only find 2.25" and 2.5" venturis, and 3" cone venturis which don't have an hourglass figure. I want to make my own, how narrow should the diameter of the skinny part be? 2.5"? 2.25"? And how long should I make that narrow part? 3"?

Cost aside, which is the best solution, the venturi or replacing the 2.5" pipe?

Will the venturi negate the higher rpm boost? Thanks!!!

 

Here's what they should look like.


Here's what they do.

These Power Squeeze venturi tubes from Car Chemistry are designed to boost low and mid-range torque, without losing top end power. These Power Squeeze venturis slide onto your existing collector or pipe and bolt on. The venturi effect allows for better scavenging and makes it possible to fine tune for maximum torque and horsepower, and reduces the likelihood of reversion. Experience faster acceleration, lower E.T.'s faster 60 ft times and more power coming out of the turns.

Here's where you can get them.

Summit Racing

 

Many thanks! I measured the pic in photoshop and it's indeed 2.5" in the middle. I'll try to get one made today, I'll post results next week after testing a bit

 

I got my venturi installed today. I showed the guy a picture of what it looked like and he made one on the spot and welded it in, all for $13

Results: Some butt dynoing I did says I got a some of the lost low end edge back, but it's definitely not back to the way it was when the pipe was 2.5". It's a midpoint, or maybe a 1/3 point.

I'm thinking about whether I should leave it as it is, switch back to the 2.5", or perhaps take the middle road and replace the current free flowing muffler with a "normal", more restrictive muffler (and more quiet, since the sound right now is a a little bit annoying and I'm a stereo guy... I would enjoy the quiet), and hope that the middle road gives me an acceptable balance between what I lost and what I gained.

Opinions?