ok i think i wanna go with a single 4 inch exhaust with my LPP longtubes. i am going supercharged and need the extra flow over my single 3 inch system... so instead of spending a huge amount of money on 2 new mufflers and a new true dual stainless setup from my local shop, ive decided on a new route... i think i can do it a bit cheaper and with a bit of cool factor in it. im thinkin of doing a super quiet 4 inch stainless muffler and then do a cutout before the muffler but after the cutout i would run a pipe next too the muffler and bring it y piped back into the tailpipe right after the muffler... this way i can have the best of both worlds... quiet when i want it and then flick a switch to unleash some nastyness!

now for my questions...

what is the a VERY quiet 4 inch stainless muffler? im looking for a borla proxs with cats type of volume... quiet but not stock quiet...

now can i use this tailpipe and make it work on my avalanche and still look nice and not hangin down? MagnaFlow 15463 4'' Universal Diesel Slip Fit Tailpipe | eBay

and where can i find a stainless y pipe that is dual 3 inch in and 4 inch out? summit racing has one but its not stainless...

and lastly what is the most trusty 4 inch electric cutout? DMH? QTP?

 

You really need to get under there and measure. 4" exhaust is VERY tight to fit, and I dont see you running two of those side by side, unless you bend down under the crossmembers, but then you have ugly exhaust hanging down.

Ive also never found a quiet 4in muffler, and ive tried single large ones and medium ones in series, 4in is loud, but this has also been on 400+in engines.

I have had QTP, DMH, and raceready cutouts, and by far I like the race ready one the best. QTP is absolute garbage, dmh is better, and race ready is the best.

Aluminzed steel will probably be fine for exhaust, you dont need stainless unless you want to get really fancy.

 

i dont wanna run 2 mufflers... just another 4 inch straight pipe after the electric cutout and then piped right back into the tailpipe after the muffler... so that when i open it up it will be a completely mufflerless 4 inch exhaust... that still exits out the back in the same pipe...

 

Right, I get that. But picture this in your mind...the cutout is a Y pipe, so you have one end going through your muffler and the other end is your cutout....you want to route that other end back to the tailpipe post muffler, but for the section between the cutout and when you go back into the talipipe you have 2, 4" pipes running side by side. Well actually for some of that you have a 4" next to a larger OD muffler, so even less room.

For going back to the exhaust a cutout y pipe turned backwards would work very well.

Like I said, you need to get under there and measure. 4" is hard enough to fit as it is, much less dual 4"...

I think its a cool idea, but like I said, you need to measure. Ive had a lot of cool ideas that were not practical, or just way to expensive to implement.

 

as far as a quiet muffler how about one of those huge stock replacement mufflers from walker... i think i seen one on summit that was like a 6.75 round body and it was 37 inches long or something? thats got to be pretty darn quiet... i currently have an 18 inch dynomax bullet before my 3 inch xr-1 round case and then piped out the back... now thats about 30 inches of small cased muffler total... so im thinkin that even though im stepping up to a 4 inch exhaust that using a 35+ inch case muffler with a 6.75 case could keep it fairly quiet... at least alot quieter than my current setup...

 

If its a straight through design its going to be louder than stock. Quiet is a pretty subjective term, but you really really really need to go measure before you start buying parts.

Im not 100% sure what the underside of the avys look like, but here is my 04 ext cab with a 4" exhaust and cutout, if you can see a clean way of running another 4" pipe from the cutout back to after the mufflers, let me know.

 

hahaha i get that whole practical thing... i just want a huge flowing exhaust thats quiet when i want and scream in your face as i pass your a$$ loud at the flick of a switch and i want it all to fit! lol i know its a tall order... i think you are right and i will take measurements tomorrow...

 

so does anyone know if that magnaflow tailpipe can work?

 

Your not getting 2 4'' pipes under there. If you do it will be a royal pita.. I do not think there is actually a quiet 4'' muffler, unless you get a chambered one which inturn would be huge.. How much hp you plan to run? Unless your making 6xx and up I think the 4'' is over kill in your case.. just my op. I had to make my own Y pipe and cut up a 3'' stainless merge for my 4'' set up..

As for that pipe, for 100 buks it is worth a shot.. I would still think you will have to cut on it to make it work based on your muffler location and all..

 

the bypass pipe doesnt have to be 4in to accomplish what you want...but Atomic is right even a 2 1/4 bypass pipe is a tight fit...whose doing the work?, I build custom exhaust and i've seen some pretty shitty work over the years, someone who knows what they are doing is probably gonna want $400 or more for that...