Exactly. If all that was done was a pipe change and no remap or anything, then this isnt a fair comparison. Now if you look at latus HD's website, they have dyno runs with true duals, and you can get a more accurate comparison.

 

I just stepped up to a "10 Ultra Ltd (103") and am debating on changing out stock headers for tru duals. I have a ThunderMax TBW removed from my previous "08 Ultra I intend to install along with a Big Sucker air filter and my Rush 2.25" slip-ons. Since the stock pipes do not have the correct bung for the wide band O2 sensors for the TMax, they would have to be removed for welding on the correct bung. With this setup, could I expect to get an increase in performance from the tru duals or more potentially a loss? The cost differential is marginal in getting the bungs installed on the stock vs buying headers with bungs already installed. The biggest factor to me is the potential difference in performance between the two options. Any advice?

 

I just stepped up to a "10 Ultra Ltd (103") and am debating on changing out stock headers for tru duals. I have a ThunderMax TBW removed from my previous "08 Ultra I intend to install along with a Big Sucker air filter and my Rush 2.25" slip-ons. Since the stock pipes do not have the correct bung for the wide band O2 sensors for the TMax, they would have to be removed for welding on the correct bung. With this setup, could I expect to get an increase in performance from the tru duals or more potentially a loss? The cost differential is marginal in getting the bungs installed on the stock vs buying headers with bungs already installed. The biggest factor to me is the potential difference in performance between the two options. Any advice?

 

Interesting topic. I have an S&S V107T in my old Glide and emailed S&S about suitable exhaust systems before I had the motor built into my bike. TDs were an approved set-up, so that is what I went with. After a break-in period I had the bike optimised on the dyno and numbers were 103HP and 102TQ, which compared well with S&S claims, so I was happy. I recently went to a SuperMegs 2-into-1 and had the bike optimised once more, by the same shop. Numbers are 101HP and 107TQ.

What they do not show is that at around 3,000rpm the TDs give about 90TQ, but the SuperMegs give 100TQ and a better curve through the low to mid-range. Bike rides much better. The only other change is around 10k miles between first and second dyno visits. I much prefer my bike with the current system.

Those of you with recent bikes would do well to have a proper stage 1 done, that is air filter as well as mufflers and a retune to optimum air/fuel ratios. Only when the bike is optimised that way will a change of exhausts be easy to compare.

 

My experience may help the thinking for anyone going down the True Duals route. I went with V&H Dresser Duals and Jackpots last year on a std 96" with A/C done and a TW6-6 and a PC-V and canned map from Fuel Moto. I did this recognising I would be trading some power gain for the great sound. Better than stock but not quite right. Put it on a dyno - full 4 hour tune with each pipe and cylinder set up separately. The gain from the tune was 4 bhp and 3 ft lbs at peak - useful but small compared to the bottom of the curve where the dreaded True Dual dip was lurking between 2000 and 2500 - in this area I gained up to 16ft lbs and the curve is now basically consistent all the way through - no dips or holes. So the lesson for me is that True Duals are prone to big dips in the low end even with the benefit of experts such as Fuel Motos best efforts (and let me stress there is no criticism here) but this can be eliminated with a decent tune. Do the tune and you will probably not be far behind most other pipes (i.e. a 2-1 that hasn't had a proper tune - and my testing against mates bikes confirms this).

I've since gone with the 107" kit from FM which is now running in but will go back on the dyno soon and already I get the distinct feeling that the raised compression is working the cam better and the bottom end feels significantly stronger than expected (compared to doing similar work on 2-1 equipped bikes) so maybe they do respond better to cubes and compression.

 

With the stock 88, if I don't want to spend a lot of money, I should just do the a/c and slip ons? Can the shop then download a Stage 1 program instead of buying a programmable fuel controller?
I don't want to lose low end torque, I just want it to breath better on the freeway.