In May ynot115 and I had the chance to compare various filter options for the 2009 VMax in combination with the X-Pipe. We performed the runs on the same day, with fairly stable conditions.

As a baseline we ran his stock bike (only TopSpeed installed to avoid the governor in 4th and 5th gear) several times to get a solid baseline.

All charts here are in SAE with smoothing set to 5. During all runs the bikes where strapped down, with a rider in the seat. Tire slippage was minimal and comparable between runs.

The tire got its share of abuse and rubber chunks are still handing down from the ceiling.

The first chart shows the stock bike compared to the X-Pipe with Stock Air-box as well as X-Pipe with Stock Airbox but the funnel removed.

The stock bike pulled about 172.5 SAE rwhps, compared to the X-Pipe making 180.2 SAE rwhps on the stock airbox. Take the funnel out and the increase on the X-Pipe was significant: 4 rwhps gain by just the removal of the funnel! X-Pipe with Stock airbox and no funnel made 184.2 rwhps.

On the X-Pipe the funnel removal (also referred to as the Aribox Mod/restrictor removal) gains you 4 rwhps - on the stock filter. This is by far the cheapest, most versatile mod. If you are still running that funnel you should seriously consider trying it without it.

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Next we looked at opening the airbox and running the setup with just the lower stacks to see the high end gains and also the loss at low to medium rpms.

This was the only test in this group without any filtering. Clearly you do not want to ever run your bike without filters. I would not even run it like that at the track. The amount of dust and particles in the air at the track is really bad for your engine. Most race engines get rebuilt after a few runs, not an option for most of us.

However this is an important baseline. It is also important to mention that so far all runs have been done without extra tuning of the fuel map past the X-Pipe setup and the stock filter.

The open airbox gains another 2.5 rwhps over the Airbox w/o funnel. Interestingly the top torque is also 1.2 ftlbs higher, while at the sames time dipping below the stock bike at about 6,000 rpm. This setup would definitely benefit from some fuel tuning. But since there is really no point in running an unfiltered setup, we did not waste much time on extra fuel tuning.

While the power dropped around 6,000 rpm, the top end and torque gains were still significant.

Now we removed the entire airbox and instead installed the Monster Velocity Stacks together with K&N 3710's. That setup we made to combine full filtering with the maximum size filters and highest stacks possible, given the room limitations of the airbox opening.

The target was not to make the longest possible stacks that stick out of the faux tank without any filters on it, but a good compromise between large K&N filters and the best possible stacks that fit into the left over room.

From testing before we knew we had found a very good compromise that works very well with the X-Pipe (so fare the best performing pipe we had on the dyno for the new VMax).

With the bike fully warmed up, the fuel map adjusted for the extra fuel needs, we witnessed a torque explosion at around 7k rpm. This setup mimics the good old V-Boost of the Gen 1 VMax. 

Power topped at 191.8 SAE rwhps with torque coming in at an impressive 121.5 ftlbs. Remember that this is with filters in place - the way the setup was designed. You can clearly see in the chart that the better tuned fuel curve, removed some of the flat spots compared to the open box setup. To be fair the open box would have done better too, if it was custom mapped.

The goal was to get the same performance as with an open - unfiltered airbox. The fact that in a few spots the Big Air Setup is even better is gravy.

All in all this should give you a good baseline comparison between common filter options for the X-Pipe. Other exhaust systems will perform differently. These charts where done on a Dynojet 250 with Eddy Current Brake, High Velocity Air Fans and the latest Dynojet software versions.

After the tuning and tests, I got a chance to ride this setup next to a stock VMax ridden by vmaxbrad. During rollons in 5th gear we saw a very similar behavior. Starting at 4k rpm the X-Pipe/Monster Air combo would start to pull away, accelerating just marginally faster between 5-6k rpm just to explode at 6,500 rpm. It was like riding two different bikes.

From 7-10k the bike makes almost 20 rwhps more over stock. Interestingly, when shifting through the gears you never leave that power band once you hit 2nd gear all the way up to redline in 5th gear.

I have received various request to post the custom maps for this setup. So far I have been hanging on to my custom PCIII install for various software reasons. It turns out that hand converted maps from the PCIII to the PCV are not 1:1 the same as the different models behave differently with identical settings. 

I am about to replace the PCIII with a PCV I recently purchased. More dyno work in the upcoming months.

Ride safe!

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