I know my exhaust is too small right now, I'm just wondering how much I will gain by uncorking it a little.

The exhaust is stock up to the 3" in dual 2.5" out magnaflow muffler, then it reduces down to 2.25" tail pipes. When I had the exhaust made up, the truck was 100% bone stock, so 2.25" tails were adequate, but now I think the 6.0L needs more breathing room. Up-front that flattened 2.5" crossover pipe can't be helping any ether.

For now I was thinking of ditching those tiny crimped up tail pipes, and running dual 2.5" pipes out the pass side, just before the tire, I would just dump it, but I think it would resonate too much. If I keep the truck as it is or go the h/c route I will get 2.5" true duals, but I've been thinking about building a custom rear mount turbo system.

 

Just an FYI I have a true dual setup and will be installing the 408 in about a month an I am going to back to a y-pipe setup and it should flow more than enough. Im going to use a pacestter 3inch ory to a corsa catback.I would put a cutout at teh y-pipe. You would be surprised how much hp a y-pipe setup can handle there are tons of fbody guys that use the y-pipe and have over 500rwhp.

 

I ran a magnaflow X factor 3 in and 3 out and the truck runs great now. It had a bit of reson noise to it new. Now that it has about 3000 miles on it u don't notice it. The muffler has a x flow in it so u don't need the x pipe. It has really livened up this 6.0. By the way true duels out back 3 all the way.