   Review of the Yoshimura RS-12 Full Exhaust System for the 2025+ Suzuki DRZ4S / DRZ4SM   We recently installed Yoshimura's RS-12 Full Exhaust on our Suzuki DR-Z4SM Project Bike, and had the ECU re-flashed. After about 250 miles of riding, here's what we think... INSTALLATION: Installation was very straightforward. Instructions are posted on Yoshimura's website. These bikes are very easy to work on, and there are only 4 bolts holding the exhaust on to the bike, all are very easy to get to, you only need to remove the side panels for access to the rear mounting locations. Yoshimura does not include a head gasket with the exhaust, we inspected ours, and it was like new, so we re-used it. PERFORMANCE / TUNING: When installing a full exhaust like this on the Suzuki DRZ4S/DRZ4SM, we definitely recommend an ECU re-flash. The bike runs pretty lean with the new aftermarket exhaust installed... we rode ours around a little after we first installed the Yoshimura exhaust, and you could just tell it needed an ECU flash... quite a bit of sputtering at low RPM and some surging too at steady throttle. After some research, we went with an ECU flash from 2 Wheel Dyno Works. You basically remove your ECU, ship it to them along with a list of the performance parts you've installed, they flash it with the appropriate map they've developed for the bike, and ship it back to you. Turn around was pretty quick, and we had our ECU back in a week. Prior to sending the ECU to them, I watched some of their very informative videos where they tested various setups on a Suzuki DRZ4S. For maximum power/torque gains, they recommended replacing the stock exhaust with a full aftermarket exhaust like our Yoshimura RS-12, keeping the stock air filter, and removing the airbox door, so that's what we went with on our project bike. After putting about 250 miles on the bike with this setup, I'm very impressed. All I can say is that the Yoshimura RS-12 exhaust and ECU flash totally changes the character of the bike. It runs so much better than stock, no more sputtering at low RPM's, no more surging at steady throttle. And it pulls really hard as soon as you open the throttle. Bottom line... an ECU flash is a must for these bikes, especially when you install an aftermarket exhaust. I couldn't be more happy with the bike now, except for one thing... keep reading the "Sound" section below... SOUND: Since I'm pretty picky about the sound of a bike, I thought I would mention this when it comes to the sound of our project bike with the new exhaust, ECU flash, and removal of the airbox door. When you replace the stock exhaust with the Yoshimura RS-12, it obviously gets louder. Many of the tuners, including 2 Wheel Dyno Works, also recommend removing the airbox door when you have the ECU re-flashed, if you want to maximize power/torque gains. We did that initially, and put about 100 miles on the bike, but I quickly noticed that removing the airbox door makes the bike even louder. With it removed, you get quite a bit of induction noise, especially above half throttle. Some people are fine with a loud bike, but the combination of a louder exhaust AND a louder intake, was a bit much for me. I personally wanted the bike to be a little bit quieter, so we've re-installed the airbox door on our bike, and now I think the sound level is just about perfect... in fact I think it sounds better than our DRZ400SM project bike with it's Yoshimura RS-2 exhaust. And I personally don't notice a decrease in performance with that airbox door re-installed (butt dyno tested), I think it's more on the dyno charts where you will notice it. Since our bike was flashed for having that airbox door removed, we'll send our ECU back to 2WDW and have it flashed again... I think they do this free of charge. LOOKS / FIT AND FINISH: The Yoshimura RS-12 exhaust looks great on the DRZ4 models. The muffler, with the carbon endcap, looks really trick, and the fit and finish of the whole exhaust is top notch, right down to the laser etched Yoshimura logo on the header pipe heat shield. PURCHASE AT THE FOLLOWING LINK: Click link below... |
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