It has been a while since we updated you on our Harley-Davidson Street Glide test bike, and we have a couple of reports coming at you in quick succession. First, we want to focus on a street legal power-up kit that we installed on the big tourer recently courtesy of Quaid Harley-Davidson here in Temecula, California. You may recall how pleased we were with the performance of Harley’s new Twin Cam 96 engine. It has huge torque, good throttle response and revs freely for such a large displacement v-twin. We wanted to see if we could improve the Twin Cam 96 engine performance with some bolt-ons available from Harley. Our goal was to keep the bike quiet and street legal.
It turns out that Harley had just what we were looking for in their massive parts catalog. The Screamin’ Eagle Stage 1 kit for EFI models consists of a freer breathing air intake system that is easily bolted on by removing the stock air filter, and replacing it with the new unit and associated parts (see the photo). The end result looks stock with the same chrome cover, but breathes much better.
Mated to the Stage 1 intake is a set of Harley’s Screamin’ Eagle Street Performance Touring Mufflers. Barely louder than stock (it is really difficult to tell), but flowing slightly better than stock, the Screamin’ Eagle slip-ons are also easy to install, and look great with your choice of end caps. Harley has several end cap styles to choose from (we chose the “Revolver” model).
Finally, there is a street legal tune in the form of a software download (reflash) that adjusts the air/fuel mixture slightly, and makes other changes to the ECU programming to work with the Stage 1 kit and mufflers.
Quaid handled all of the installation work for us, and the end result for parts and software cost came out like this:
| Part | Cost |
| Screamin’ Eagle Stage 1 Kit | $139.95 |
| Screamin’ Eagle Street Performance Touring Mufflers |
$399.95 |
| Revolver-Style End Cap | $39.95 each |
| Stage 1 Software | $149.95 |
What about the results? As stated, the bike is still extremely quiet, and it loses virtually no low end torque. Throttle response is better everywhere, and slight horsepower and torque gains can be seen as low as 2,700 rpm. Above 3,700 rpm, the already strong Twin Cam 96 becomes an entirely new beast that loves to rev! Instead of the motor wanting to flatten out just above 5,000 rpm, it now pulls much harder from 4,000 rpm to just over 6,000 rpm. The effective rev ceiling is raised roughly 600 rpm, but the big power boost covers the entire top half of the rev range. Peak wheel horsepower increases from roughly 69.5 to 75.
Take a look at the before-and-after dyno chart here.
The bottom line is this. If you want a faster Harley that remains at a neighbor-friendly sound level, these modifications are impossible to beat. Stay tuned for another update on our long-term Street Glide.
