I was wondering how bad the factory downpipe restricts the exhaust. For tuning all I run is a 40hp FICM tune. The cat and muffler are ******d as well. I’d like to run a 4” exhaust, but if I’m not going to benefit, I’d rather spend money elsewhere. My thoughts were to run a 3.5” downpipe and a 3.5” muffler to quiet it down a bit. Any suggestions?
Stock exhaust
- Thread starter Diesel625
- Start date
79jasper
Active member
Typically stock downpipes are fairly restrictive.
I wouldn't go any smaller than 4".
Sent from my SM-G892A using Tapatalk
I wouldn't go any smaller than 4".
Sent from my SM-G892A using Tapatalk
03_PSD
Member
I'd get 3.5" downpipe and donaldson muffler to help quieten it.
sootie
Well-known member
- Joined
- Oct 3, 2012
- Messages
- 11,849
- Reaction score
- 36
waste of money upgrading the down pipe on a on a tune only truck.
Zeb
New member
I’m with Sootie on this one.
If you want to clean up and quiet down a butchered up system MBRP makes a nice 4” downpipe back system.
A factory exhaust isn’t nearly as restrictive as a lot of people think/claim it is.
What I’m going to say can be disagreed with and probably picked apart, but I think it is accurate.
My wife’s Excursion has 205/30’s, CNC Fab Stage 2 hpop, RCD Stage 1 cam, ODawg intake manifold, Irate T-4, SX-E 63/68/.83, the up pipes are wrapped with DEI Titanium header wrap, and the turbine has a Turbo Performance Products blanket on it, CSF 6028 intercooler,
If you want to clean up and quiet down a butchered up system MBRP makes a nice 4” downpipe back system.
A factory exhaust isn’t nearly as restrictive as a lot of people think/claim it is.
What I’m going to say can be disagreed with and probably picked apart, but I think it is accurate.
My wife’s Excursion has 205/30’s, CNC Fab Stage 2 hpop, RCD Stage 1 cam, ODawg intake manifold, Irate T-4, SX-E 63/68/.83, the up pipes are wrapped with DEI Titanium header wrap, and the turbine has a Turbo Performance Products blanket on it, CSF 6028 intercooler,
Zeb
New member
Sorry, accidentally posted before I was finished typing.
It has a custom fuel system, Jesse Warren tuned it, and it has a DPC Heavy Duty triple disc converter, a a STOCK (catalytic converter and muffler still there) exhaust because she wanted it quiet.
On Bo Layne’s Super Flow dyno it did 508/938 and 511/940. Let it cool down, bumped the load up 5% and raised the starting speed 5 mph and it did 509/942 and 511/943. Let it cool off and separated the exhaust where it was downpipe only and it did 509/943.
If a truck is close to stock power there isn’t a lot of point in changing the exhaust other than for it to sound cooler.
It has a custom fuel system, Jesse Warren tuned it, and it has a DPC Heavy Duty triple disc converter, a a STOCK (catalytic converter and muffler still there) exhaust because she wanted it quiet.
On Bo Layne’s Super Flow dyno it did 508/938 and 511/940. Let it cool down, bumped the load up 5% and raised the starting speed 5 mph and it did 509/942 and 511/943. Let it cool off and separated the exhaust where it was downpipe only and it did 509/943.
If a truck is close to stock power there isn’t a lot of point in changing the exhaust other than for it to sound cooler.
03_PSD
Member
I totally agree with you. I'm stock (tune only) but did 3.5 dp and killed the kitty. My lower egts have been the only benefit.
