Been proven on dynos that the CAT does not restrict flow until around 100hp (but it will eventually restrict flow). So on a "stock" bike, it doesn't really matter. So you really don't see any gains decatting a pipe until over 100hp. Now that said, most people that are building motors over 100hp will want every bit of power, and a X pipe or 2:1 will make more earlier in the RPMs. TDs will make more towards the top end, generally. Most of the gains made in a Stage I are from the A/C and a good tune. A CAT with a tune and upgraded A/C will still peform as well as a decatted bike with a tune until around 100hp, it'll just won't sound as nice. After 100hp the decatted bike will start making better hp.

I do agree that the 09 non CAT head pipes are very adequate and quality pipes for over 95% of builds. I do not buy into that the MOCO designed these for max flow though, they designed a motorcycle that was reliable in stock form. Look at the 2012 SE catalog. Their 120 bike has an stepped header X pipe on it, not a stock pipe. If all of their stock stuff was "the best" they would not be able to market upgrades and the entire SE line would go away.

 

The advantages of true duals (2-2) are sound and heat reduction.
1) Sound will be more stereophonic because you'll get 50L-50R in the mufflers vs. 30L-70R with the stock headers
2) Heat reduction will be greater. I didn't have a cat in my 09 headers but switching to Dresser Duals significantly reduced heat on the right side.

The disadvantage of true duals is that you'll lose a little bit of torque in the low end. Nothing dramatic though. 2-1-2 headers generate more back pressure than 2-2.

 

posted twice

 

posted 3 times. Arrgh!

 

The difference in performance on a stock or Stage One bike between an '09 without the cat and a '10 is next to nothing. The cat doesn't become a restriction until you start moving serious air.

De-catting a '10-'12 is not the same as running an '09 pipe, as the O2 sensors are in a different location and will crosstalk causing fluctuations in the VE tables when reversion occurs. The Fullsac and Jackpot headpipes correct this issue, and also do a better job of scavenging the exhaust. There is a modest improvement in horsepower and torque to be gained from the more efficient design. V&H has not correctly located their O2 sensors, and doesn't perform as well as the other two headpipes. This has been documented on Doc's dyno, and there are several threads (including V&H's response to Doc) on other more technically-oriented forums.

It is my opinion, backed up by years of tuning my bikes, and through conversations with top-tier tuners that a properly designed 2:1 exhaust will make the most power and torque on a Harley. The 2:1:2 X-pipes from Fullsac and Jackpot are extremely close to 2:1 performance, and true duals leave quite a bit of power on the table.

 

I can tell you that removing the cat made a marked inprovement in throttle response. I try to blip the throttle before going to first gear on a cold start. With the cat, the engine slowly revved up and down. Without the cat, I can come closer to blipping it. I haven't done the stage 1 yet, so I've still got the restricted A/C.

I don't buy it that pulling the cat won't give you more power. It may be wishful thinking, but it seems like I have more power now than when stock.

 

I also remain very skeptical since cats are a restriction, pure and simple.

I would like to see data from a test, same bike, same day, same dyno with a before and after to show no difference. Stock heads, stock cam is fine.

The sound difference alone dictates a difference in airflow.

 

We have tested this many, many, times over. Here is a chart comparing the stock catalyst head pipe to our Jackpot 2/1/2 head pipe on a completely stock bike. These tests were done on the same bike, same day, back to back.

2010 Ultra Limited 103" Stock

 

05Train....Can you elaborate a little on your statement the 2:1:2 Fullsac and Jackpot are superior to V&H Power Dual header? I know looks can be deceiving but all 3 pipes look identical in build. I am in the market and ready to purchase new headers for my 11 FLHTCU but everday I read something different on the pros/cons of each.

 

That's where I'm at my man.