Ford Focus ST Forum banner
1 - 16 of 16 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Hello,

I just bought a 2016 Focus ST, I love in California and since moving Isn’t an option for now does anyone know if it is bad to do a catless DP and resonator delete? Could this hurt the engine in any way? I plan on doing minor upgrades like IC and intake but I don’t want a loud exhaust.
 

·
Super Moderator
2017 Kona Blue ST1
Joined
·
2,951 Posts
This is my exact setup. Depo catless with full factory exhaust. It does slightly increase the sound of the turbo but it's negligible exhaust DB change at best. I would be willing to experiment with an aftermarket resonator but only after I do the math for a helmholtz resonator in tandem.
 
  • Like
Reactions: roundhouse

·
Premium Member
Joined
·
1,867 Posts
I don't believe it will harm anything, but the stock exhaust is restrictive, so it's not going to do much for you vs an aftermarket catback.
The stock exhaust isn’t that restrictive, you can get away with it on a BT build easily. The DP becomes an issue before the catback does.


A nice quiet setup is a DP on the stock exhaust.


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
1,634 Posts
The stock exhaust isn’t that restrictive, you can get away with it on a BT build easily. The DP becomes an issue before the catback does.


A nice quiet setup is a DP on the stock exhaust.


Sent from my iPhone using Tapatalk
I guess I meant "more restrictive" vs a 3" Catback.
 

·
Registered
Joined
·
276 Posts
I would leave the cat on and remove the resonator.That thing is a monster and has a smaller inside dia.than rest of exhaust.
 

·
Super Moderator
2014 ST3. Garrett Powermax turbo, Thermal Turboback, CPE intercooler, JBR intake, Innovative RMM
Joined
·
4,553 Posts
only after I do the math for a helmholtz resonator in tandem.
My brain hurts trying to even think about accounting for that, due to the massively variable exhaust temperature. Something tells me that ballparking it and building an adjustable length one will be more effective.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #11 ·
Thank you all for your comments and input. I will follow up with you all after I decide what I am going to do.
 

·
Super Moderator
Joined
·
10,058 Posts
This is my exact setup. Depo catless with full factory exhaust. It does slightly increase the sound of the turbo but it's negligible exhaust DB change at best. I would be willing to experiment with an aftermarket resonator but only after I do the math for a helmholtz resonator in tandem.
I have an MRT axle back; it has a "J" tube helmholtz built in. I could measure it for you. Running just the factory resonator through the axle back there is no drone what so ever.
 
  • Like
Reactions: roundhouse

·
Super Moderator
2017 Kona Blue ST1
Joined
·
2,951 Posts
I would be very interested in placement and length. I'm looking to build in a adjustable length set up.
 
  • Like
Reactions: TurboGT

·
Super Moderator
Joined
·
10,058 Posts
I would be very interested in placement and length. I'm looking to build in a adjustable length set up.
Placement is easy; it's an axle back set up, so the resonator sits where the muffler used to.
382586

But, I believe the important factor is the volume. Measuring from where the right side tip is welded to the pipe, around the outside to the end of the "J" tube is 43 inches and the pipe is 2.5 inside diameter.
 
  • Like
Reactions: SSgtjrobertson

·
Super Moderator
2017 Kona Blue ST1
Joined
·
2,951 Posts
Thank you!
 
1 - 16 of 16 Posts
Top