I have a 05 silverado 4 dr. 4+4 z71 5.3
i have already installed a volant intake and i want to add a exhaust and throttle body spacer
with the exhaust i think i want to go with a 70 series flowmaster because they have the most torque gains and the least in cab resonance. i have heard with my truck though that i need the smallest pipes i can get to maintain the backpressure so that no torque is lost. what i dont know is what confiiguration of muffler i need for the most performance. flowmaster offers: a 2.25/3.00 dual/c, a 2.25/2.25 dual/dual, and 2.50/2.50 in 5 configurations:C/C, C/O, O/C, O/O, and O/OSS. i have no idea what all the letters stand for.

with the throttle body spacer i want to get a tbs torque curve all i want to know with this is will it have any tuouble rubbing with the Volant?

also i drive alot on dirt roads and understand that the dirt can get to some of the filters, what is one of the better off road filters?

 

all those letters are location of the inlet and outlet ports on the muffler ie. C/C is center in center out and O/C is offset in and center out. depends on the location of the muffler into relation to where your pipes come to the muffler. for your truck i would do a 2.5 at the most to keep the reasonance down.

 

so no matter what will i lose torque or with certain setups can i keep it the same or even gain?
would the single in single out be the best for performance or the double in single out
and with the diameter is it the in or out that needs to be smaller to maintain backpressure

 

the bigger your pipes get the more torque lost on your model, those trucks need a certain amount of back pressure to run proper. so far the best ive seen to get the sound and not mess with the performance is a single in dual out muffler. i would keep the inlet smaller then the outlet so that its not flowing exhaust out to soon.

 

what size comes stock
and if i only did a single in single out would it be better than single in dual out?\
also with the transdept torque curve would it rub with the volant?

 

I have a 2005 z71, 5.3 vin B. K&N series 77 intake, BORLA Dual exhaust and hypertech programmer. MY truck DID NOT AGREE with the throttle body space, it made idle surge, CHK engine lite came on, not idle correctly.. So just make sure if u make the purchase on the tb spacer you can return it if it doesn't work!!!

 

05's have electric fans dont they? if they do i wouldn't think clearance would be an issue with the intake and tbs

 

No issues with rubbing with the volant and TBS. Not even close. And throttle response gain is really good, as well as noticable power increase. I have the smoothe bore, but would get the torque curve if I bought again. For exhaust single in 2.5" dual out any size 2" or greater. The exit doesn't matter if it is too big as the premuffler pipe will keep your backpressure. Also single out vs dual out changes nothing but the look. So, single in, dual out 2.5" will be great.

 

The farther back the "reduced pipe size" the farther up the rpm band the max torque will climb. Reduced pipe before the muffler would be lower rmp torque gain. Smaller "after muffler" pipes would be closer to mid-range torque gain. If you notice on our truck the dual pipes and dual cats have decent sized daimeter, then into a pretty big single pipe, then after the muffler it is slightly smaller. Kind of "choking" the exhaust at the end of the system to gain back pressure. Thats why I believe that if you do dual exhaust (dual outlet muffler) then smaller pipe size would be the closest to stock you can get over just using a single pipe.

It would be interesting to see how the truck would drive with a smaller inlet into the muffler.

 

I have thought about cutting my pipe before the muffler and putting in a reducer, just don't want to cut my pipes since the guy did a good install job. I may wait and get some electric cutouts to put in there, they are just soo expensive.