[VernSchillinger]

Keep in mind also that more than the absolute HP & TQ gains is where in the RPM band do the gains occur and what is the trade off associated with the gains. Most flow (intake or exhaust) related gains tend to occur on the top end of the RPM band (where people don't tend to spend a whole lot of time) and often result in some loss of torque on the low end of the band, where its more important.

Anybody who can definitively say they can consistently feel a 10-13hp PEAK gain on a 400hp vehicle, ought to put in an application as a test driver for an F1 program. A lot of the gains that people talk about are the perceived gains from things like change in the sound and volume of exhaust note.

All of the above being said, there are instances where large displacement vehicles with poor heads or other aspects of airflow management can see gains from certain bolt ons. Case in point, some of the lesser tuned Chevy and Ford small block V8s.

Getting back to my earlier point, I don't thinks there are a lot of leftover "scraps" to be had on this engine.....at least not ones that can make an appreciable difference.

I'm not trying the diss the product refenced, by any means; just saying that the dollars are going to be spent for the change in exhaust note and thrill associated with the same, as opposed to an meaningful gain in performance.