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I put the straight-through TORs on this week, and I can tell you there was no loss of torque on the bottom end. That is a true statement, for whatever that's worth. So what's with the "required" back-pressure?




Blanket statements don't always work since everything is inter-dependant and varies set-up to set-up.
Depending on the length of the pipes and the volume of air moving through the system you might require back pressure to help scavange the combustion chamber during the valve overlap period.
The pipes might be short enough that the rebound pulse doesn't even develop and the exhaust gases can expand directly into the atmosphere.
The pipe might expand ala megaphones to allow the gases ample volume to exit...the variables go on and on.
Generally speaking, a small restriction (backpressure) somewhere along the chain breaks the rebound pulse and that helps the motor breathe. That's about it.
In your case, you put on straight thru pipes, did you gain any power? And was that gain broadband or limited to one RPM range, say in the higher zone above 3500rpm? Maybe you didn't GAIN any torque (rather than losing torque) and that's worth thinking about.

A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)