So, I have a few questions concerning 2 into 1 pipes...

I have 2008 Fat Bob with Cycle Shack 2.5" Slip-ons, SE Stage 1 Air Cleaner, and a Power Commander V. I plan on doing a 103 Big Bore kit over the winter.

I know that 2 into 1's are better for overall performance of a bike. A local shop owner suggested using Vance and Hines Pro Pipes for the best performance. So my questions are...

Do I lose any performance with the 2-1-2 tommy gun exhaust on my Fat Bob in comparison to a straight 2 into 1 exhaust? I do like the look of the tommy gun exhaust.

Is there a substantial difference between 2 into 1 pipes? (i.e. V&H Pro Pipes vs Thunderheader vs V&H Big Radius 2 into 1 pipes)

I did try to do a search looking for other threads but I really wasn't able to find the information I was looking for.

Sorry in advance for my newbishness!

Thanks!

 

Well, if you're referring to using the stock exhaust versus one of the other ones you mentioned, I would say YES! You are losing performance...The stock exhaust is much more restricted. I went with the Bubs Lakester 2:1 exhaust. One reason was because the headpipe is the same bend as the stocker. I plan on having the heat shields modified to replicate the Tommy Gun look.

Here's a pic of the Bubs...

 

Black D&D Fat Cat on 2008 FXDF.

 

The biggie with your stock exhaust is, IMHO, the catalytic converters. As in -- Where are they? Probably in the collector, right? If you can eliminate those (intelligently) and create a smoother flow (key) into your muffler pipes.............

Then the 2 into 1 will still out perform your stockers.

The question is, do you really care that much? Is it enough 'performance' to offset the cosmetic difference you prefer? My neighbor took his 2 into 1s off. Didn't like the look. They were the V&H Pro Pipes. He didn't like the sound at low RPMs, either. Now he's got the V&H long shots. I think they're long shots. Equal length. Whatever. I know he pisses the OL off every now & then when he cranks it up early in the morning or late at night. But she likes him, so she doesn't stay POed for very long. Amazing that somebody you like can do something and somebody you don't like can do the same something and your reactions are different. Human nature.

I too like the look of the Tommy Gun exhaust. I think it looks badazz. Some 2 into 1s look pretty decent while some look like the back of my nutz. But none of them look as good as the TGs.

As far as which 2 into 1 performs best? Who knows? Who can tell? It has a lot to do with your bike and how it's tuned. One set might perform better on one bike and not perform as well on another.

Good luck in your decision making.

 

I'm pretty sure the '08s didn't have the cat. in the pipe . And that being the case , the performance of that stock pipe is pretty darn good . Somewhere on here is a Dyno sheet showing the hp/tq curves with a stock 2-1-2 exhaust like yours compared to a quality 2-1 , and the difference is VERY minimal . If it were me...I'd keep the stock head pipe , and go with a quality slip on , which I think you said you all ready have .

 

The Owners Manual says they do (pg 28) but all the owners that have taken their exhaust systems apart say they don't.

Very confusing.

It probably doesn't.

 

I love the way my ---Vance & Hines Pro Pipe HI-OUTPUT sound and perform (except they are very hot against the leg (I have ordered the wrap)



this note below is from their product page:

Pro Pipe Hi-Output is a purpose-built addition to the Pro Pipe family of 2-into-1 exhaust systems. Every aspect of Pro Pipe Hi-Output’s design is singularly focused to yield maximum horsepower by improving the volumetric efficiency of heavily modified engines.

After countless dyno tests Pro Pipe Hi-Output was built utilizing tuned length headers that step from 1-3/4” to 2-1/4” to optimize exhaust gas velocity and scavenging while also maintaining the perfect balance of exhaust back pressure, assuring crisp throttle response and maximum roll on power. In addition, the merge collector features handcrafted internal knife edging to further improve scavenging efficiency through the collector.

Following the collector, the megaphone immediately tapers out to a 3-1/2” muffler body that expands to 4 1/2” for increased baffle area. Our exclusive Vance & Hines baffle features reverse cone engineering that allows maximum power yet omits the perfect exhaust note rumble for any hi output motor. Keeping its focus on performance, Pro Pipe Hi-Output retains the signature cues of the Vance & Hines Black Line with its high temperature ceramic coating and contrasted machined billet end cap.

 

I think thats on the CA models only though. I'm pretty sure they started using them on most bikes for 2010. A 2-1 system over a stock system anyday! You have to look at more than just peak #'s and focus more on where the torque curve is. But cycle shack slip-ons are some of the best ones out there. I think you'll be happy either way you go.

 

Only CVO Fat Bobs had cats in 2008 or 2009.

The exhaust gets more important as you go up in displacement. At 96 inch, there is no real difference between pipes, more power here, less there, Sound and style differences yes, but street power not really. I'm not sure even at 103 or even 110 inch if there is much of a difference, but a bigger exhaust on a bigger motor makes more of a difference.

If you are looking for max HP, go with a 2-2 and ride at higher RPMs. 2-1 typically make more torque at the lower rmp, but then have an annoying dip in the middle RPM ranges.

If you intend to keep running closed loop (and you should), stick with the stock head pipe if you like its looks. Some of the aftermarket stuff places the O2 sensors poorly. I think you won't loose any power even at 103 inch. The CVOs are 110 inch right? They use the same head pipe with cats welded in.

The reason it doesn't make much difference is that any HD exhaust is way too short, so you are just making a bad situation a little worse or better. Its still a bad thing and won't effect much in the end. Many of the dyno charts comparisons have a stock bike set up compared to the new pipe plus tune... and most, if not all of the improvement is due to the tune.

If you want that last 1 HP, however, I noticed that even the best pro tuners disagree on the best pipe, they each have their favorites to tune, and it varies from motor to motor, and tuner to tuner and month to month. Just saying, on a late model, you should be more concerned about style and sound than anything else until you are well over 110 inches.

 

I went V & H 2-1 and they are great. Performance is amazing, sound is terrific. I am very pleased with my decision after much research