Im getting my 350 lt1 bored and stoked to a 383 with forged internal. Im planing on bolting on lt headers but idk if i should go with true duals or an ory, then a cat back. Im wondering if a 383 needs less ristrictive exhaust, and what muffler should i use. Can someone help me please.

 

The larger displacement, assuming you have the heads and cam to support it, will produce a larger exhaust volume. How much exhaust you need will depend on the HP level.

There are 3.5" and 4" catbacks available form Mufflex. I ran a 4" Mufflex at the 800HP level, and when I pulled the heavy (50#) catback off to replace it with light weight duals (Borla XR1 in each collector, each with a 3" pipe toward the rear axle and a turndown) there was no significant difference in HP. A buddy of mine, pushing 1,125 LT1 HP through the 4" Mufflex had the same results - no HP restriction, just a bit of a weight penalty.

 

If your worried about restrictions with the exhaust you could always run a 4'' Mufflex catback. Overkill though unless you are making big HP.

Edit; I see someone beat me to it.

 

if ur getting the LTs then just go with 2.5 TDs withy bullets dumped right before the axle, trust me that is more than enough for up to 500HP and it will also sound much better than the ORY+catback

 

mufflex exhausts are extremely loud and not really needed. just buy a normal exaust.. if you feel the need put a cut out in it.

 

In my opinion the 2.5" true duals dumped before the axle are just plain annoying while driving. Don't get me wrong I love the sound of my beefy V8, but unless it is used for strictly racing I would not get them. I have the LT's with a X pipe that run into dynomax bullets and I can barely hear my radio. I am going to go ahead and run the dual's over the axle and into a slp style cme when I can find one. Like the car in the sticky in the exhaust section on this site. That should quiet the car down significantly and should not have hardly any loss.

https://www.camaroz28.com/forums/sho...d.php?t=598251

 

The Mufflex 3.5" and 4.0" catbacks are available with either the Flowmaster 30-series race mufflers (single in/single out) or the SpinTech single in/dual out stainless mufflers. The Flowmaster is definitely loud with the usual 2,500RPM drone, but (and its obviously highly subjective) did not sound "extremely loud" on my car. I rode in the Mufflex owner's SpinTech equipped LS1 and is was not loud at all. There is a sound clip of the SpinTech on the Mufflex site.

I will add that my Mufflex 4" (Flowmaster) setup had a custom 3" Y-pipe, built/installed by Mufflex in their Trenton NJ shop, and it was equipped with dual 3" CarSound cats. The cats were flanged so they could be replaced at the track with the Borla XR1's. That may have produced a bit of noise reduction, compared to a setup without cats.

 

i have true dual 3 inch on my vette with the exhaust all the way out the back and its louder then hell. literally. i have lt's and slp mufflers. i would like to put an x pipe in it at the least. if not swap it to a magnaflow system with an x pipe and a center muffler. i will see if i have a video

 

i had a mufflex on my 3rd gen. it had lt's a custom y pipe into the 4 inch system. it had a flowmaster in it. it was soo incredibly loud. i had an afr headed 10:1 383 and a 4k stall. you couldn't hear yourself think inside that damn car. swapped to a 3 inch system and i could hear the radio and not have to scream at the top of my lungs to talk to the person in the passenger seat