Me and Fake Indian had the same exhaust set up, later on he added an aftermarket Ypipe and it made quite a bit of difference to the sound of the two systems side by side. The OEM ypipe is very restrictive compared to aftermarket ones.
Daryl, I thought that too but the truth of the matter is more problems occur with Nismo/Ichiba/OEM Ypipes cracking HFC's or Decats than the Stillen, not to mention the short life span of flexis, 2 year max warranty usually. I did read some of the r&d notes on it a while back, can't remember exactly why they chose this way but I think it had something to do with the Angles involved in the design. Theres no getting away with it, Motordyne is the best but it does come at a cost. Bang for buck the Stillen would be next choice.