LB7 down pipe swap is a PITA. That is the only model that is not a single "V" band. Can cause you to drink heavily and bleed profusely.
Best bang for the buck would be down pipe and removing muffler, but would not be the easiest.
LB7's are also loud without a muffler FYI.
bleeding profusely is no exaggeration. And you'll need to eat your wheaties to bust the bolts holding the downpipe on loose.
And i strongly recommend running a muffler, without one, at 70mph you will not be able to hear yourself think
I don't mind the extra work and blood to get the best gains for the buck, I sort of wear that stuff like a badge on honor, especially if it's someone most other people forgo. It looks like Magnaflow has the only stainless downpipe, I'll probably snag that one.
I used to have a straight piped LB7 back in 2005ish and I don't remember it being
that loud, but thanks for the heads up, we'll see how much the lady can stand. Allegedly she "wants an exhaust" on the Duramax, lol. Loud is sort of objective, my hearing is 1/2 gone anyways... If it gets ridiculous we'll get a muffled 4" system later.
From what MBRP told me the LML was on stock tune with only the downpipe change.
On the LBZ we did, it was "emissions legal" so we left the cat, and we used the MBRP muffler. The article is in the current issue of Diesel World on a Work Truck (page 80 in Feb 2014 issue). The owner really likes it. He is pulling down 17 MPG with the HEAVY service bed fully loaded!!! But that is with No Limit Tuning & Design EFILive tuning now, and the HP also bumped up to 511 with 885 tq thanks to the EFILive tuning...
SOAK the bolts with penetrant before and during the removal will help a lot, but it is still a pain in the but!!!
My LB7 uses the ProFab downpipe and Banks 4-inch exhaust with muffler (with ProFab castflow manifolds and uppipes, Fleece LB7 drop in turbo, Fleece EFILive tuning and Banks Intercooler and boost tubes) and it is making plenty of power (543 and 1006 tq) for a 360,000+ mile engine running stock gears and HEAVY 37-inch tires mounted on KMC Enduro true beadlock wheels (114 lbs each wheel/tire combo).
If it is going to be a Daily Driver I recommend sticking with the muffler from any of the major exhaust manufacturers, they are not too restrictive and will help with drone and such especially on the freeway!
Sounds like a stout truck, the one we just got has 298k on it and now the mods have begun. I appreciate that additional info, I almost wish I could do a before and after dyno test for exhaust #1 vs stock. According to your results and Idaho Rob, there are decent gains to be had with a downpipe upgrade.
I get Diesel Power whenever my mom gets me a subscription, but never see Diesel World magazines around town.
Side note: Since I've got some folks here that have been around the block, is the
BD Full Bore manifold a worth while modification? Visually it looks like there are gains to be had there. Seeing it drop in price to $150, it seems almost worth it to avoid EGT probe manifold cracks with it's predrilled and tapped probe hole. What are you guys thoughts on those? I see people claiming it "achieves engine balance" but that might be reaching...
