MXA TEAM TESTED: PRO CIRCUIT 2020-21 YZ450F TI-6 EXHAUST SYSTEM

WHAT IS IT? The Pro Circuit Ti-6 titanium exhaust system is one of many exhaust options that Pro Circuit offers for the 2020 YZ450F. The Ti-6 system is designed to meet AMA Amateur competition requirements, but will not pass FIM/AMA Pro sound requirements. When unboxing the system, you get a head pipe, mid-pipe, three pipe springs and a muffler with a removable USFS-approved spark arrestor installed. The spark arrestor is held in place with a 4mm Allen head bolt that can be easily removed to go between off-road and closed-course riding and racing.

WHAT’S IT COST? $1118.21.

CONTACT? www.procircuit.com or (951) 738-8050.

WHAT STANDS OUT? Here’s a list of things that stand out with the Pro Circuit Ti-6 exhaust system for the 2020 Yamaha YZ450F.

(1) Fitment. The Pro Circuit Ti-6 titanium exhaust system utilizes all the stock hardware (besides the heat shields) and provides three exhaust springs that mate up better to the Pro Circuit pipe. To install the Ti-6 system, you will need a 10mm socket, 6-inch extension, swivel end, ratchet and a spring puller. First, you want to remove the right-side number plate to get to the muffler bolts. Next,  loosen the two mid-pipe clamps for easier removal (the Pro Circuit system will not use these clamps). Remove the top 10mm muffler bolt and washer, and the lower muffler bolt and washer. The mid-pipe is held on by a single 10mm bolt that is the same length as the lower muffler bolt. To get the mid-pipe off the head pipe, you have to wiggle and pull at the same time. The last step is to take the head pipe off. It is fairly straightforward, except for how tight it is to get to the bolts that hold the head pipe to the cylinder. MXA uses a 6-inch extension with a swivel end to get to the two bolts. Be careful with the head-pipe gasket, because you will be reusing it when installing the Pro Circuit system. To put your new Pro Circuit exhaust on, just reverse the above steps. Do not tighten any of the bolts until everything is on the bike. This lessens binding.

(2) Weight. It is no secret that the stock YZ450F muffler is big and bulky, but there is a good reason. Believe it or not, the stock YZ450F muffler helps support the subframe. The Pro Circuit Ti-6 titanium system is just under 2 pounds lighter than the stock system while still keeping its needed strength. 

(3) On-track performance. It should be noted that the stock YZ450F system is good for an OEM unit. Test-rider complaints about it were: (a) The power had a light-switch response off idle that made the power feel jumpy. (b) After the jumpy throttle response, the stock powerband laid down until the rpm climbed above 9000 rpm where the real power was found. (c) Even with the extremely popular TP-3 map, our smaller test riders felt that the combination of the snappy hit and lazy transition into the middle were negatives.

These problem areas are where the Pro Circuit system excelled. It delivered smoother bottom-end power that transitioned through the midrange with a more hooked-up feel. It made the bike easier to ride out of corners. The midrange is where the Pro Circuit system really shines. Those who like to short-shift will reap the rewards and get the most out of the system. The mid-range had a livelier feel that test riders could use to their advantage when trying to hop over braking bumps on long, fast straightaways. We also noticed longer clutch life. How so? Test riders were able to roll the throttle on without having to rely on the clutch to keep skipping the power across the low-to-mid lull.

WHAT’S THE SQUAWK? It was hard to find something to complain about on the very well-constructed Pro Circuit Ti-6 system. But, if we had to pick one thing, it would be the carbon fiber end cap ($99.95). After enough tip-overs, the cap will eventually crack. Pro Circuit sells the cap separately, and it is easy to replace.

MXA RATING: The Pro Circuit Ti-6 titanium exhaust system is a work of art. The craftsmanship of the system is second to none. Not only does it look good, it has the performance to back it up. It delivered what test riders wanted out of our 2020 YZ450F—smoother power delivery down low without sacrificing anything on top, making it enjoyable for test riders of all skill levels.