D&D Exhaust

[tslick]

I've been holding off on buying a new exhaust system and thought I had made up my mind to get the D&D Fat Cats, but now I'm hearing the the D&D Boarzilla system is one of the best 2-1 performance exhaust systems available for performance Twin Cam builds. Anyone have first hand experience or seen and heard this system?

[Dyna Jim]

I've been holding off on buying a new exhaust system and thought I had made up my mind to get the D&D Fat Cats, but now I'm hearing the the D&D Boarzilla system is one of the best 2-1 performance exhaust systems available for performance Twin Cam builds. Anyone have first hand experience or seen and heard this system?

Tslick I spoke with Don at D&D about the Boarzilla, and it's only design for big inch engines not 95's. In fact he put it to me to the affect of 107+ inch engines was what it was designed for. It's got 1 7/8 primary tubes which on a small engine will kill lots of low end power. You may want to talk to D&D direct before you get to set on that pipe (I can get you don's number if you'd like). I am direct now with D&D and can get you the boarzill, but unless your going big I think it's a mistake.

My .02

[tslick]

Thanks Jim and I will call D&D. I am going to 103" real soon (heads in this week) so I was thinking of these for that build. It's great to get information like yours before jumping in with both feet. I'll let you and others who may be interested what D&D says. Also, would like to hear more about your baffle/muffler deal with the Fat Cats.

[tslick]

Ok I talked to Don (D&D Tech Support) and he told me that I would experience a loss on the low end with the Boarzilla exhaust. It is a more free flowing system that they developed for 107-113" motors. He also said that he knows folks who have them on 88" motors now that have plans to build up. They are willing to suffer, for now, at the lower end, but wanted to get the boarzillas with the knowledge that they will need them once they build up. I didn't get the impression that with the 103" motor there would be a significant low end loss. It depends on the nature of the build ie compression. Also I told him I had the race tuner and he said that I could recover some of the loss with proper tuning. Don will even help in that area with maps that can get me or others close if D&D pipes are purchased. I'll mull this information over, but see no real issues with putting boarzillas on my particular build. Also, just a note that the boarzilla pipe is upswept (Fat Cat is not) which may make a difference for those of you that have lowered bikes or are real aggressive in the turns.

[Dyna Jim]

Tslick,
I'm glad Don could give you the upfront first-hand knowledge you needed to make a educated choice. I just hate to see people getting into the bigger is better routine and then later finding out less is more. I used to see this all the time in the race engine industry. Someone would want this huge engine, when in fact it was always easier to get more Hp per cubic inch from a smaller race engine. Harley's are not race engines so this rule doesn't really apply, as they will never make much more than 1.1-1.4 Hp per cubic inch. Case in point I've built some small block super comp engines that made 2.3-2.4 Hp per cubic inch, when you start talking big inch engines it's much tougher to get close to that kind of number. Just use your head, realize a Harley is never going to be a big HP engine, and build yours with your own ideas. No matter what pipe or head you put on a Harley, it's never going to be very Volumetric effiecient, they just don't fire right for that... :shifty:

[tslick]

That is a good analogy and certainly worth consideration. I started out with very little knowledge and just plain didn’t care about the performance impacts the exhaust system had on my bikes. I just wanted it to look good and sound good. I still want those two things but have educated myself to a dangerous level about the trade off’s. Basically you just have to see performance results from like builds and select the system that has the best potential to work well on your bike. I say potential because there are no guarantees that any one system will work given all the other pieces and parts that influence performance. Performance, quality, and support are extremely important to me and I’ll use those criteria to finally make a selection. The Boarzilla seems to meet the criteria for now. Thanks for the help Jim