APPLICATION: Most late-model mxers (Tested here on the ’08 RM-Z450)

PRICE: $799.99

MOTOCROSS.COM RATING:8.5

CONTACT:www.fmfracing.com

            Last week, if you were paying attention, we did a little update on the 2008 RM-Z450 and how a change in the ignition mapping, combined with an aftermarket pipe, makes for a vast improvement in the power characteristics of the big RM-Z. The pipe that we tested that day, and have been riding with since then, was the FMF Factory 4.1 with a PowerBomb header.

            Here at Motocross.com, we’ve tested a lot of FMF pipes, all with varying degrees of success. But before we get into how this set up performed, we’re going to take you through some of the key features.

            First of all, the entire system is made from titanium, which FMF claims makes it the lightest full system available on the market. And just like most of FMF’s four-stroke exhaust systems, it is designed with what FMF calls “Factory Forward” engineering. In other words, the system is moved forward, shortening the mid-pipe and muffler length to help centralize the mass of the system. And despite the shorter muffler, FMF has still managed to keep the sounds level at a minimum. Holding the system onto the bike is a machined aluminum hanger on the top of the muffler along with springs on the mid- and header-pipe that help to dampen vibration and hold the pipe securely in place. Finally, bolts are added where the headed connects to the cylinder, giving it an even more secure hold. Also for those who want a different look, the muffler is available in both natural titanium and blue anodized, and for some more money, you can even purchase it in carbon fiber. As for the header, the PowerBomb is designed to increase flow by opening up a key portion of the pipe. This innovative design also acts almost like a pre-muffler, allowing for the shorter muffler that we mentioned earlier.

            Like every other FMF system that we’ve tested, the fit and finish is exceptional, and the entire system fitted right up to the RM-Z with little or no trouble. When we initially rode the bike, we did so without any change to the ignition mapping. In this state, the system did add power to the Zook, however, it didn’t make a huge noticeable difference. The power revved out slightly further, but still had the annoying characteristic found on the stock RM-Z450 of popping and flattening out once in the upper echelons of the powerband. As for the low- to mid-range power, it was boosted slightly too, but like up top, it wasn’t a huge difference. Once we adjusted the ignition mapping on the bike, it made a huge difference, as the power enhancements from the FMF system truly shone thru. The normally electric-feeling power of the Suzuki was boosted slightly to have a little more of a hit. Don’t get us wrong, though, it still remained smooth—which to us is a good thing on a big 450—it just had a little more oomph. With the FMF system, the low end and mid range was improved, while over-rev—which was an area that needed the most improvement—was boosted to the point that the bike pulled incredibly well down fast straights. We haven’t been riding too long with the system mounted up on the bike, but we can tell that in our experience, FMF exhaust systems can withstand quite a bit of abuse.

RATING

            We decided to knock a few points off the FMF Factory 4.1 Full Titanium system for the simple fact that if you bolted it straight up to the bike, the power gain isn’t incredible. With a few tweaks to the ignition mapping, though, it’s an entirely different story. FMF has told us that they will be selling a programmable box to adjust the ignition mapping called the EFI Power Programmer, and it should be out soon. Despite this small complaint, at the end of the day, like always, we were happy with how the FMF system performed. It adds power, shaves weight, and looks good while doing it.