MK III VW's
We built our MK III Jetta 4 years ago..... And we knew that weight would be a problem, so getting the weight down was job 1. We come off the track with the weight at 2370 on average, depending on the fuel in the tank...After we got the weight out, we worked on the ECM, Had GIAC burn us custom chips, made good HP/Torque, but could never get the A/F ratio down to 13.1.... was usually in the 11.5-12.0 range, way rich but quick..... Colin from Techtonics also burned us custom chips burned, , still could not control the A/F ratio..... It was not until we installed a MegaSquirt, by Atlantic Auto Works in Melbourne Fla, that we were able to get the A/F ratio to 13.1, and it is adjustable, made more HP and Torque, use a NewSouth Peformance Intake manifold gasket and reduced the intake manifold temp by nearly 40 degrees, Nice part........ We also used a the 4.25 final drive and were happy with the performance, But again Atlantic Autoworks convinced me to go to a 3.9 FD, because like so many have said, the stock cam will not pull over 6200, and if it does, the cam is not stock. We shift at 6000, because our dyno sheets showed how quickly the power dropped off over 6200, but the engine makes great torque, it pulls the 3.9 easily....so at places like Daytona the 3.9 is just the better gear, and I suspect will work better at the Sebring 12 hour course. Spring wise we run 650's in the front and 750's in the rear, and massive multi rear bars, none in front.
Also keep the stock cross dash bar......There is another MK III Jetta in CFR. Mike Ogren has a good shell. We bought a complete spare 96 Jetta for $300. and it had almost no rust, VW built twice as many Jettas than it did Golfs. It you are in the SE, Get with David Boles or Jeff Linfert at Atlantic Auto Works, they are the go to Guys on VW's in my estimation...... David Ellis-Brown