I know you asked T3, but I've kept pretty good records of my performance gains after each modification to my Yerfdog 3206.
Stock Spiderbox configuration: 13/40 internal gears, 13T engine sprocket, 31T axle sprocket, and 743 20 30 Gates belt.
All measurements were taken with a Garmin Etrex handheld GPS, on concrete, with a set distance (approx 300'), on the same "track".
22.3 MPH as is from previous owner (stock tires, slightly deflated, stiff front suspension)
23.1 MPH performance coil, performance CDI (both orange from Ebay), no air filter and 125 main jet
23.7 MPH opened muffler opening (1/2" stock VS. 3/4")
24.9 MPH home ported head and port match intake manifold
26.3 MPH MAX SPEED (first run on street)
25.2 MPH 10g Dr. Pulley sliders with cleaned/lubed CVT, and deglaze clutch and bell
29.8 MPH MAX SPEED
26.8 MPH New tires and bearings (22" rear), FMF slip on exhaust, UNI air filter with 6" extension
33.2 MPH MAX SPEED
27.2 MPH 8" extension for air filter
33.0 MPH MAX SPEED
28.0 MPH NCY CDI (orange with aluminum housing)
33.0 MPH MAX SPEED
All readings were taken with all upgrades added to one another. Only the air filter extension was substituted.
Round 2 Test and tune
28.6 MPH 12 gram Dr. Pulley sliders and header wrap for 7"
35.3 MPH MAX
30.1 MPH A11 cam installed (needs larger pilot jet)
38.9 MPX MAX
Last test and tune session with basic "stock" engine:
29.6 MPH with stock rollers
37 MPH MAX
30.2 MPH with Dr. Pulley variator and 12g sliders
38.3 MPH MAX
I tried getting readings with a 6", 7", and 8" red neck tube extension, but they were all around the same speeds in accel. I didn't have the jetting nailed down yet with the A11 cam until after I made the passes. The kart was blubbering off the line.
Ended up using 35 pilot, 2 1/2 turns on the mixture screw, and a 122.5 main jet for good reults.
So no improvement from the last test session. 12g sliders in the stock variator seemed to work best for me.
OK, so now I have the 62mm BBK kit installed
32.7 MPH in 300'
Max speed 40.2 MPH
Time to install the good stuff......
