ok i have tried this on different posts but figured i would do my own thread instead of asking on other threads and hijacking them.
ok i have an 08 reg cab shortbed 2wd 4.2L 5 speed. i put a cold air intake on and got different headlight assemblies. for it. i made some GT emblems for it and put them on. yes i know its a V6 but its not too shabby in the speed department. please no negative remarks about the emblems. but anyways, because i am trying to make it sporty, i want the look of dual exhaust out of the back but since it is a V6 i dont think spending $ on an aftermarket muffler is justified. i have heard many mufflers on the V6 and they do sound better but you can still tell its a V6. so i am keeping my stock muffler and setup. only mods will be done after the rear axle about 1 inch after the last hanger. i want to cut the exhaust, put a Y pipe on it and run two 2 or 2.25" pipes out of the back below each end of the liscense plate. i also have two dual tips so it will look like 4 pipes. i had a 96 trans am that had that look and i loved it so i want it again. this is only for looks, any performance gains are not expected. my stock exhaust sounds fine to me. i have had a few people tell me its sounds pretty good at idle. at WOT from outside it sounds like a V6 but from inside it sounds almost like an 8 but not quite. the whole setup is the stock 2.75" pipe run thru the stock muffler and past the last hanger, then Y'ed into two 2 or 2.25" pipes and then ended with two dual tips that have two 3" outlets on each tip. i will have to take my spare tire off and most likely my hitch. i dont tow anything so i dont need the hitch on there.
ok so after that, does anyone think it will sound better or worse? i shouldnt lose or gain any airflow because i am modifying such a small part of the exhaust and its at the end of it. buying a magnaflow or flowmaster or anything is not something i want to do right now. maybe later after i get a tuner and some other stuff, i might put a SI/DO magnaflow on it but thats far from happening right now.

 

Your going to lose some back-pressure after the muffler. Meaning a slight loss in Tq in the lower end of the RPM spectrum. The factory pipe is a 2.5" into the muffler, 2.5" out of the muffler. If you split this 2.5" outlet into (2) 2.25" pipes that is equivalent to 4.5" piping... Understand? If anything you might actually quiet down your factory exhaust even more by doing this. I don't want to steer you away, but I mean if your only goal is to achieve a "corvette" style looking exhaust, do it. At least you have the right mindset on the idea by not expecting ANY performance gain or improved sound, but only looks.

 

if your keeping the stock muffler running tips back wont change the sound much..i know a guy with a chevrolet that didnt want sound he just wanted look..and y'd it behind the muffler and ran tips back..doenst sound any different.

i would y it back with 2.25 pipe. and if you want a magnaflow, you could get a longer one and Y it off there as well.

 

ok so in order to keep the backpressure, i have to go with two 1 3/8 in pipes. around that. i have to go below 2 3/8 becaus the opening for the tips is 2 3/8. plus the one looks like it was squished a little. i would rather go with 2" pipes. like i said i dont tow anything so losing a little low end torque would probably be made up with losing hte weight of the spare tire and hitch. but now i have to think about the size pipes. the stock exhaust is 2.75", at least at that last hanger and i dont see any flare out anywhere so its gotta be 2.75". thats OD. i measured it and got 2.756" OD at after the last bend.

 

Don't worry about back pressure. Just run a Y pipe with 2.25" pipes to the back and some nice tips. You will never notice a difference with just changing that small amount of pipe and still having the stock cats and muffler.

 

thats what i figured. its too little area and the air flow is the same up until the Y. thanks for the inputs. this mod will not happen for a few months tho. gotta let the snow go away first. got a few more things up my sleev to for looks. but they are BAD-A$$. you will see...in the springtime

 

Just run a chambered muffler and Y it or use a SI/DO.

 

i dont want to get a new muffler. im not too impressed with the sound of all of them. i can still tell its a V6 so i figure why do it? the only way i would replace it is when it rots out or if it falls off from hitting something or gets damaged. IF that happens i would go with a magnaflow SI/DO. or possibly look at the mufflers that Banks offers. so far the banks ones are the best sounding to me but i am pretty sure they are kinda expensive. my stock system doesnt sound bad at all from inside. outside isnt bad but you can definitely tell its a V6. from inside you would have trouble figuring it out i think unless you know what a 4.6 sounds like from inside a NBS.

 

IMO, the biggest issue you face is moving that spare. those exhaust pipes arent going to do you much good if your on the side of the road with a flat, and relocating it into the bed is pointless

 

A competent exhaust shop can route the pipe around the spare tire with plenty of extra room... Regardless if it's Y or true duals.

 

yup, thats the one problem i am having. i do still have roadside assistance for another 1.5 years or 14k miles. but after that, i donno. maybe i could put it behind my seat. i donno, ill figure it out sometime.

thats the problem, im figuring it out and getting the pieces myself. gotta take it somewhere to be welded on. so the thing is...can I figure out a way to get it around the spare or not? well i have a few months to think about stuff. i already have the adaptors and tips. all i need now are the elbows. just have to figure out the angles and stuff.

 

IMO, just put a Y after the stock muffler and run the dual pipes accordingly. It will look sporty and hopefully no one will be able to tell it's a V6.

 

^ I thought you got banned...

 

I thought I did too. I guess the mods realised this place was boring without me.