I had Rinehart Extreme duals with 4" mufflers. It was tuned earlier this spring with my SERT and made 86.34 hp & 95.64 tq SAE. I bought a used RB racing Pro stock Spyder 1 3/4" with a welded in baffle. Just wanted to do my own comparison. Same shop & tuner. The new pipe flows a lot better and made the bike real lean, so of course it was down on power. The tuner kept adding fuel and the #'s kept getting better but fell just shy of the Rineharts
Air fuel ratio was getting real close but...At idle the bike would start to go real lean and stumble then right back to normal range again. He thought maybe I switched the O2's or powerwashed the bike, etc. But everything looked fine. So for now he shut off the O2's until he can figure out what is going on. He is going to send my info to the Dr, hopefully he can come up with something. I don't have any final #'s because of this problem. He didn't charge me (yet) until we can straighten this out and give it the final tune. The weather was 25-30* hotter with 30-35% more humidity. So this doesn't help. Hopefully there is a little left.
For what its worth, the bike runs fine in open loop. I would of never known the difference! Still pulls great too.

 

What made you want to change it if it was running so well...or was it your not liking the sound and trying to find the right tone? We can all relate.......

 

Sick of going to bike events and seeing rows of Rineharts I never cared for the look of the headpipe on the Extremes. The rear pipe runs over the oil dipstick and then under the bike to the left side. Kind of ugly.
Thought I would gain a little low end torque going to a 2 into 1, plus I like being different! I really like the look and sound of the Pro stock Spyder. Its a little louder and has a more angry racey tone.

 

Here is my RB Racing pro stock spyder.

 

I sure like the look of the exhaust on your bike. It really works with the colors.

 

Motor being an air pump, I'd say your on the money with the drastic Temp/humidity change.

 

Hummm I see what you mean.....right nice set a pipes. Whata they sound like? Whose got those for sale?

 

http://www.rbracing-rsr.com/lsr21prostock_spyder.htm I have the 1367.

They are a little louder then the Rinehart's. With a little more pop, and a little growl on decel. They just have more of a race bike note. This model has a welded in baffle, they offer a quieter one called the blackhole. Not cheap but I haven't seen another one like it around here. I just hope I can get it dialed in correctly to give a fair comparison between the two. My bike is a stock 96" with a set of Andrews 48H cams.

 

FWIW that is a nice looking pipe! What part of MI are you from?

 

Once you go 2 into 1, I'll wager you'll stay with them.