brandon_6667

iTrader: (3)

Current mods in my sig. I'm currently still running my factory 5.3 manifolds/ypipe/etc with my new 6.0 and i'm sure they are definitely robbing some serious power. I live here in CA and was going to go with some doug thorley try-y's to stay smog legal but they are real expensive and are only 1-5/8 primaries with a 2.5" collector.

Do you guys think I should go with the thorleys and a true dual 2.5 exhaust or would there be alot more power to be had with going catless and running some pacesetters with 1-3/4 primaries and 3" collectors? I am trying to decide if the difference between thorleys/cats and pacesetters/no cats would be worth the trouble of swapping the whole exhaust system over every 2 years to pass smog?

also, if I do go catless with longtubes should I go with 1-3/4 primaries or 1-7/8? is there a huge difference?

Blackpanther99

iTrader: (8)

Pacesetter long tubes with 1 7/8 primaries! With 3" true duals or a 3" Y pipe.

brandon_6667

iTrader: (3)

3" duals wouldn't be overkill?

Driver311

iTrader: (1)

No 3 inch duals will be perfect, or 3.5 inch single. These motors want a ton a flow. I personally dynoed and gained 10whp and 15ftlbs going from 3inch single to 3.5 inch single and my buddies 6.0 with a magnacharger woke up a lot going from a corsa dual exhaust to dual 3 inch. Basically the bigger the better with these motors. The pacesetters make a lot of power for the price. Go pacesetters with dual 3in and you will be shocked at the gains. Talking 35-40whp from exhaust bro.

Steve-O-08

iTrader: (5)

I run Bassani Mid's with stock cats/y-pipe on my Silverado with my 370. Definitely not ideal but had no issue passing smog with my cam (similar to your Vinci Trucker) and a fairly aggressive tune. Ran a set of 1 7/8's long tubes with a 3" ORY and the truck really liked them. Pulled them because of fitment issues. Will be going with 1 3/4" LT's when she get's put back together.

brandon_6667

iTrader: (3)

So sounds like the dual 3" would be the best. what do you guys think would be a good choice for mufflers? The 6 year old flowmaster 40 series I have now sounded ok with the 5.3 but has alot of drone under light throttle with my 6.0 and just dosen't sound very good. I was thinking a DI/DO magnaflow, or dual SI/SO magnaflows after an x-pipe. I still want it to be loud but want it to have less drone and sound a little cleaner under part throttle.

gamble686

iTrader: (3)

I would suggest getting it registered in rural AZ where you have no emissions. Otherwise I would find somewhere you can get your emmisions done with high flow or dummy cats. If you can rock a high flow cat after the YPipe you should pass emissions on the sniffer and you can remove the codes using hptuners or efilive to pass OBD2 testing. As for cat back magnaflow single 3.5" for a muffler and 3.5" all the way back would be great. Headers I think you would benefit from 1 7/8" primaries and 3" collectors. By uncorking your exhaust with your setup you may see 50hp gains. A LQ9 with a cam needs to breath bad, but you can go overkill contrary to what some say. I have seen a 6.0 G8 lose 17hp going from stock mufflers to 3" dual straight pipes. You will need some back pressure, but not too much either it's a happy balance you need to find.

brandon_6667

iTrader: (3)

So if I go with full length 1-7/8 headers with a 3" collector I will probably do dual 3" all the way back with a 3" xpipe and either dual Magnaflows or a DI/DO magnaflow. what do you guys think?

Richardman1992

iTrader: (5)

I would run the single 3.5" and my vote for a muffler is spintech after going from a blowmaster 50 series I believe to a spintech 8000 I'm never using anything other then spintechs again! Good sturdy muffler, sound amazing dumped, not sure how it'd sound exiting out back or to the sides

Vortec350ss

iTrader: (20)

Thats a small cam in the LQ9. I have a buddy with an SSS that runs that same cam. It runs really well. I'd recommend the standard long tubes over the tri-y, and I'd also recommend the larger 1 7/8" primaries. Thats what I ran prior to my cam swap (although I had a lot more planned) and they worked great.