Quote:
Originally Posted by Hib Halverson
Exhaust emissions and beating guzzler had nothing to do with the existence of the port throttles. In fact, guzzler was never and issue with the LT5.
The secondary port throttles exist soley to improve low speed torque and throttle response.
Actually, most C6ers with cars having NPP do not "...replace them". Admittely, some folks do swap an aftermarket exhaust for the stock dual-mode system, but more C6 people retain the NPP system but add an device ("Mile2Wild", "Exhaust Commander" and similar products) which allows them to manually control the exhaust bypasses.
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If it was for low speed torque then they didn't do a very good job.
My Z stock was peaking 330RWTQ @ 5200 now i make that at 2500 and peak is right at 400 @ 5200.
If you look at Z's with ported top end and no secondaries they make anywhere from 300-330tq @ 2500-3000rpm and close to 400 peak.
If you tune the car right you will loose nothing at low speed,my Z with huge cams for a 350 can cruise at 1300 rpm and get 24 MPG highway.
A lot more has been done with todays technology in the tuning department for our Z's.
If you ask most will post there before and after dyno sheets.
If it wasn't for guzler tax then it must have been for emissions,back in the old days when we had that thing they call emissions (rollers) i forgot my secondaries on it failed next day with no changes just kept secondaries off it passed.(same location)
On the C6 ZO6 mufflers there are half dozen for sale as we speak on top of the half dozen i have bought the most recent (2 weeks ago) the gentleman replaced them with B&B's,there's a few ZO6 guys that replace them,you might not be one of them.
Most car shows and dragstrips i go to i see most have replaced them.
Pete