ATVPT

Product Review
Product:	- HMF UTILITY FULL EXHAUST SYSTEM
Machine:	- 2004-2005 Suzuki Twin Peaks 700
Review Date:	- July 2007

Introduction:
I don’t believe in replacing anything OEM unless there are performance gains. I have done lots of mods to my machine since I brought it home in December of 2004. Click here for a list. So why have I waited until now to replace the stock exhaust on my Twin Peaks 700? Partially because I have dropped coin on after market pipes before and I didn’t get much change in return. I wanted something that delivered proven horsepower, had stainless steel pipes, and wasn’t too loud, and didn’t break the piggy bank. Until I found all that, I decided to modify the stock can by completely gutting it and adding a replaceable packing with inner core and removable aluminum end cap. It had a sweet, mellow rumble without being too obnoxious, but my butt dyno wasn’t that impressed. I already had good off-idle response due mostly to the after market CDI and an intake modification by Mike Strider, but my pipe didn’t flow like it should and ran out of juice in midrange and on top end.
Contents:
The full system consists of an Aluminum canister and end cap with the stainless rear cylinder header pipe welded to the stainless front cap. It is a two-into-one design, with the stainless front header joining into the y-pipe just ahead of entering the can. The welds are beautiful, clean and continuous and the stainless material will not rust out like my 2 year old steel stock pipe did. The aluminum body has a brushed finish to it. Not too highly polished, not too dull. It matches the finish of the stainless header pipes nicely. My kit also contains the quiet core, clamps, hex key wrench, screen type spark arrestor, sticker, and instructions.
Installation:
Installation required removing the lower plastic forward and rear of the left sideboard. You can leave the front and rear fenders on. The fit and finish of the pipe was good and I have no doubts that HMF did their homework on fitting this pipe to my TP700. One interesting thing that made the install easier is the addition of a separate piece or “spigot” that is attached to the rear cylinder head of the V-twin. This piece is basically the rear cylinder header flange with a stub pipe welded on. This allows you to slide the rear header straight over this spigot and tighten with a special clamp. The design works great, although I think that clamp could be built a bit stronger. Be sure and use fresh exhaust gaskets or chances are, you will get a leak (Suzuki part# K1100-91894, Kawasaki part # 11009-1894). No special tools were required to install the pipe. Access to the front cylinder is fairly straight forward, but the rear is in kind of a tight spot. You can reach the header retaining nuts with an open end wrench fairly easily but a universal or flex joint mounted on a 24” long ratchet extension (or longer) will certainly speed up the job. The procedure in HMF’s directions was pretty good. Just remember to place the clamps on the pipe ends prior to installing them and orient them so you can access the tightening bolt easily. Be sure to replace the stock heat shield on the front header pipe. Although the HMF header pipe is larger in diameter than the stock pipe, the heat shield mounts will enlarge enough to fit and the stock hardware is re-usable. It’s not as pretty as leaving it off, but it will keep unwanted heat off your left leg.
First Impressions:
Let me just cut to the chase here and say that the HMF delivers more power. I am totally satisfied with the upgrade. My V-twin pulls noticeably harder now all the way to top end. Midrange to top-end is definitely improved, especially with the quiet core removed. I find myself getting to the other end of familiar straight-aways noticeably quicker. The Butt-dyno is happy, and I am still running a bit rich. You see, I have restricted the intake a bit just to make sure that I wouldn’t run lean until I could re-jet my bike.
A Word About Jetting:
I definitely suggest that you re-jet your bike when installing a new exhaust, or doing intake modifications. The obvious reason is to take advantage of the power gains, but you could also do damage your engine by running it too lean. The best way to jet is to take your bike to a local shop that can tune your machine on a dynamometer. It is well worth the hundred bucks or so to get you’re air to fuel mixture dead on. Mike Strider at Chapman Performance “dyno” tuned my machine when he installed his custom intake cross-over tube some time back. This modification, together with an enlarged snorkel, required size 200 main jets for my machine to obtain the optimum A/F mixture. I will return to Chapman for another dyno run in the near future to tweak the jetting once more. I can also compare horsepower numbers to my modified stock exhaust since the pipe is the only thing that has changed since the last time. I will post that information in a future update.
Real World Results:
There were 8 of us out trail riding in West Virginia and we came upon this huge reclaim. It had a really wide, long gravel straightaway that was reasonably level. Even though we are all set up for trail riding with coolers and boxes on the racks, we just couldn’t resist lining them up. The contenders were a bone stock King Quad 700, a Prairie 700 with a moose module, Douglass rattlesnake rims w/GBC Dirt Tamer tires, a bone stock Polaris 700, and a snorkeled Rincon 650 with some heavy 26”mudlights. I was running heavy ITP type-5 rims with Kenda Bounty Hunter’s, not my lightest set-up. In about 500 feet I got the Kaw. by 2-3 bike lengths, the King by 3-4, and the Polaris by maybe 6. The Rinny came in last, but that was expected because he’s set up for mud. In closing I would like to add that my bike was "slow" when I bought it new. It happens. Some machines come together better than others. I lost most straight line races to similar bone stock machines before I started modifying. After installing trail proven after market accessories, I have seen gradual improvements over time. Adding this pipe really pulled everything together and I’m totally satisfied with the balance of power, functionality and durability. I’m finally to the point to where I feel like my bike is complete. …that is until someone in the crew gets a Big Bore Kit of course ;-) So if you are still running the stock pipe and want to be the big dog in the pack, the HMF can certainly provided your machine with the bark!

Pros:
	More seat of the pants Power. Dyno results to come.
	Crisp, tuned exhaust note, Not too loud WITHOUT the quiet core I.M.O.
	Not much louder than the stock pipe with the quiet core installed.
	Initial fit and Finish is superb.
	Lightweight, good looks and corrosion resistance.
Cons:
	The included clamps are a bit weak, but they work OK.