I was looking at the dyno graphs at the hmfengineering.com site, and it didn't look like there was much of a difference between the charts for the slip on with stock head pipe, and the full system. Just a little bigger gap on the top end.

My question is this:
Sometime down the road I will be getting a big bore kit (perhaps the Trinity 680 kit). Would I be better served getting just the slip on for ~ $150 or just go all out and get the full system for ~ $350?

 

HMF's dyno numbers do not look very impressive at all. I'd really look for a different pipe setup. I've seen much better numbers for other pipes. I read on another Yammy website that someone had HMF install and jet the full system and they were very disappointed in the results. I'm waiting for a pipe shootout in one of the magazines, it's supposedly in the works now.

 

The Numbers are true, compared to other manufactorers. And how do they not look good? Go to the dunes and see how well the HMF does against all the other systems. Sparks, DMC, and HMF are the top of line, and the HMF isover $100 cheaper than sparks and $200 for DMC

 

Hey, I am the guy on the "other Yammy forum" who didn't like his HMF. Things change. I have there full system with silent core and DynoJet kit. I jetted it for a full-flowing exaust so when I ran against my buddys' Banshee... he smoked me!!! I then proceded to take off the airbox lid to lean it out a bit. I gained a lot of low and mid compared to stock. Satisfied but lacking just a bit. HMF just sent me the free-flowing core to replace the silent core which has three half circle baffles inside. I test it out tomorrow.

I called DynoJet and spoke to the guy who designed and tested the jetkit for the Raptor...with the HMF pipe. He said the Silent core has the same power as stock so get the standard HMF free-flowing exaust system and with the minor airbox-snorkle mod... it should rip.

Tomorrow is the big day to test out noise and performance...I will let you know!

 

dunno about you guys, we have run a HMF slip on against a full big gun setup, the slip on matched it and had a better torque curve. I think HMF are honest with tehr numbers, I run against the soo called Sparks 50 hp setup (full pipe / big flter /rejeted) and it was no faster...............

Get it on a dyno and get the mix sorted, to rich robs power, most people over jet to hell thinking big jets = big HP......... remeber that the dynojet needles flow way more fule than the stockers and the dyno jet jet numbers are not comparable to a standard mikuni jet number because of the way they cut the jet orifice....... you use a way smaller dyno jet jet number than stock mikuni jets.....

Kiwi

 

Kiwi_Craig: One of other system i'm considering is the Sparks full system. Have you seen this pipe in action? Have you noticed any pros or cons with the two systems, other than the price?

 

Well my brother got his HMF slip on today. It's loading up on top end. This is w/ the jetting he had for his full DMC. We will be comparing all day tomorrow. We've tried full DMC, BG, & Graydon systems. The BG is the one I kept. I'll have more info tomorrow! We will also take them up Sand Mtn at LS Utah next weekend. This will tell alot as well as this is a grueling hill.

 

the Sparks pipe is very well made as is the HMF. IF money is of no concern then just go for what looks the best...... but if you are like me and cash does matter then the HMF is the best value for performance pipe out there. For a slip on it sure embarrasses alot of "full systems"

as for jetting, every system is different and should be dyno'ed to get the mix spot on. Big jets do not= big HP........

 

I just tested the full HMF exaust tonight. I am very impressed. It did not make as big a difference as a 2-stroke pipe but I feel it is worth the money. Not too noisy either. Tomorrow I will drag race my buddys' Shee to compare with last time...

 

I have the full HMF system on my Raptor, and I am veryy satisfied. I went riding this weekend in the sand and have stock tires wich are bald, no tread at all and I was destroying stock Raptors and Banshees with no problem. Also beat a 440EX with DMC exhaust. Didnt get to race any modded shees but I gunned it side by side with piped Banshee and pulled on him. All I have to say is this system Rocks. I seen a guy with a E series and he wouldnt come out and race me. Give the HMF a try and you iwll not regret it, I promise you.