The exhaust note was actually quieter than stock to the point that you may have mistaken the 1JZ for an electric motor. I began to suspect that the exhaust might be overly restrictive when there were some boost fluctuation issues at full boost, approximately 0.7 bar.
So without carrying out any further or more scientific diagnosis of whether this issue was indeed caused by the exhaust....
Out with the blow torch.
Decided to just remove the center silencer and keep the stock exhaust muffler for the moment.
The offending item removed.
Initial impressions are that the engine seems to be revving easier with less restriction but then again I might be crazy and imagining things. The engine now has a note but it's still very very quiet. Unfortunately there's an irritating resonance now on light throttle openings. Its not very loud but still.....
However, one things that I did notice was that the maximum boost was up slightly to 0.8 bar vs. 0.7 bar with the silencer installed. This doesn't really make much sense as the wastegate is still the same and theoretically should have maintained the same maximum boost of 0.7 bar.
Can I notice any increase in power due to this 0.1 bar increase in boost pressure?
Most definitely........ NOT.
I may be crazy but not that crazy. There seems to be an improvement in response but can't say I can feel any power increase......
Hmmm...... maybe time for a straight through muffler.