Catted vs. Uncatted Downpipe

underdonk

Well-Known Member
Joined
Jan 6, 2021
Threads
44
Messages
1,879
Reaction score
1,876
Location
USA
Car(s)
'21 Supra 3.0 Premium
I was reading a threat last night which for the life of me I cannot find now where someone stated that the difference in horsepower and torque gains between a high-quality catted downpipe and an uncatted downpipe were only single digits. This surprised me as I thought the potential with the right tune and other appropriate exhaust components was much higher. How true is this? Does anyone have any dyno runs with both types of downpipes or have found any vendors that claim certain numbers for both types? I cannot find any. I have an AA catted downpipe on order and an uncatted aFe downpipe sitting in my office. I'm not sure I want to deal with a CEL ('21 untunable car) for single digit gains from the uncatted version (plus there are some issues with the aFe downpipes that makes me want to return it but they're being... difficult... about shipping).

Hope everyone is keeping the rubber side down!
Sponsored

 
  • Like
Reactions: zrk

zrk

Well-Known Member
First Name
Zack
Joined
Apr 20, 2021
Threads
79
Messages
8,330
Reaction score
13,536
Location
Chicago, IL
Car(s)
2021 Supra - Nocturnal Black
I've heard the same and ended up going catted. I don't need every ounce of power. The car is already fast out of the gate. I'm not looking for insane dyno numbers, just enjoying wrenching again and driving something that's fun and fun to work on.
 

Sangeof

Well-Known Member
First Name
Sanju
Joined
Jan 16, 2020
Threads
7
Messages
84
Reaction score
102
Location
Queens, New York
Car(s)
2021 GR Supra A91 Refraction
Around 10ish is your gain. This is from a reputable tuner I spoke to. I have an AA catted dp and itā€™s on my car now but Iā€™m swapping out for my AA catless just to squeeze out as much as I can from my recently bench unlocked 2021 a91 edition. Iā€™m able to swap out for emissions tests so it may not be worth it for everyone else. Iā€™d say you should just install the AA catted dp. It hasnā€™t given me any CEL and it will give you some gains over stock.
 

Extreme Power House

Well-Known Member
Gold Sponsor
First Name
Mike
Joined
Nov 7, 2019
Threads
85
Messages
1,590
Reaction score
992
Location
Las Vegas
Website
x-ph.com
Car(s)
18 BMW M4, 13 Mustang GT
It ranges from 3 to 6 percent depending on the fuel used

Stage 1 91 octane: up to 22% HP / 25% TQ
Stage 1 93 octane: up to 25% HP / 25% TQ
Stage 1 E30 octane: up to 28% HP / 27% TQ
Stage 2 91 octane: up to 26% HP / 28% TQ
Stage 2 93 octane: up to 28% HP / 28% TQ
Stage 2 E30 gas octane: up to 34% HP / 30% TQ
 

Jackyl tm

Well-Known Member
First Name
Tim
Joined
Apr 11, 2021
Threads
31
Messages
488
Reaction score
349
Location
Newburgh, IN
Car(s)
A91 Edition, C230, Mazda Protege
Around 10ish is your gain. This is from a reputable tuner I spoke to. I have an AA catted dp and itā€™s on my car now but Iā€™m swapping out for my AA catless just to squeeze out as much as I can from my recently bench unlocked 2021 a91 edition. Iā€™m able to swap out for emissions tests so it may not be worth it for everyone else. Iā€™d say you should just install the AA catted dp. It hasnā€™t given me any CEL and it will give you some gains over stock.
When was your ecu date?

Also, op I have the aa catted downpipe and it's amazing. The peace of mind of not throwing a cel etc is worth it. I'm untunable as well, those few HP you won't notice. Sounds amazing too! I have videos
 

VA90

Well-Known Member
First Name
Chris
Joined
Oct 19, 2020
Threads
11
Messages
792
Reaction score
948
Location
NoVA
Car(s)
2021 Supra 3.0 Premium
Just about all the gains, more or less, come from relocating the cat from its location on the stock system. Nowadays, the actual converter itself just isn't as restrictive as it might've been 30 years ago. That delta is even smaller when you're looking at a high quality catted downpipe. So yes, you're unlikely to detect a performance difference comparing catted to catless. But I didn't want to deal with the stink, the rasp, and the CEL for a nominal increase in HP. That's why I went with an AA catted downpipe.
 
OP
OP
underdonk

underdonk

Well-Known Member
Joined
Jan 6, 2021
Threads
44
Messages
1,879
Reaction score
1,876
Location
USA
Car(s)
'21 Supra 3.0 Premium
Thanks for all the opinions and information everyone has shared on this thread. I've decided to just run with the AA catted downpipe. Much like @zrk, I'm not about getting the absolute most power out of the car that I can. Just something fun to drive on the street and do a track day about once a month. Maybe that will change as the car gets older and I turn it into a dedicated track car, but for now, I'm just going to stick with the part that won't throw the CEL and add a little sound to the exhaust note (which I love what I'm hearing online from this component). I'm going to return the aFe uncatted downpipe. They don't seem to want to pay for shipping even though the main reason I'm returning it is they stepped down one of the pipes incorrectly inside of the downpipe. I'm happy to post pictures (I have before) if anyone is interested. I'm quite disappointed in their customer service.

Also, @Extreme Power House, I'm lucky enough to have 93 octane everywhere here in KY.
 

Sangeof

Well-Known Member
First Name
Sanju
Joined
Jan 16, 2020
Threads
7
Messages
84
Reaction score
102
Location
Queens, New York
Car(s)
2021 GR Supra A91 Refraction
When was your ecu date?

Also, op I have the aa catted downpipe and it's amazing. The peace of mind of not throwing a cel etc is worth it. I'm untunable as well, those few HP you won't notice. Sounds amazing too! I have videos
03/16/20
 

black_sedan

Well-Known Member
First Name
BR
Joined
Sep 15, 2019
Threads
14
Messages
639
Reaction score
540
Location
Northeast Florida
Car(s)
a90 Supra, Ford Raptor
I run a catted DP. Had a similar tuned car on the same dyno and tuner with a catless DP and it was making almost 20hp and 35tq more than my catted DP. My tuner did mention to me that was about the norm in his experience.
 
OP
OP
underdonk

underdonk

Well-Known Member
Joined
Jan 6, 2021
Threads
44
Messages
1,879
Reaction score
1,876
Location
USA
Car(s)
'21 Supra 3.0 Premium
I run a catted DP. Had a similar tuned car on the same dyno and tuner with a catless DP and it was making almost 20hp and 35tq more than my catted DP. My tuner did mention to me that was about the norm in his experience.
Did he happen to say how much more HP and TQ a catted downpipe usually gives over a stock setup?
 

Escapist

Well-Known Member
First Name
Alex
Joined
Aug 28, 2020
Threads
9
Messages
564
Reaction score
698
Location
Pensacola, FL
Car(s)
2020 GR Supra, 2016 Yamaha R1
I run catless because for one, I live in Florida, and two, I like to hear the turbo.
 
OP
OP
underdonk

underdonk

Well-Known Member
Joined
Jan 6, 2021
Threads
44
Messages
1,879
Reaction score
1,876
Location
USA
Car(s)
'21 Supra 3.0 Premium
I run catless because for one, I live in Florida, and two, I like to hear the turbo.
Huh. Never thought about the ability to hear the turbo more using an uncatted downpipe.
 

65sohc

Well-Known Member
First Name
Ken
Joined
Mar 8, 2020
Threads
11
Messages
466
Reaction score
271
Location
Fresno, CA
Car(s)
65 GTO, 69 Corvette, 65 Corvette 427, 23 Corvette
I run the CG Precision 5 inch catted. Because of the size it flows 20% better than other catted pipes. On e50 my car traps at 128 mph which is a good indicator of how much power it is making.
 

H2O_Doc

Well-Known Member
First Name
Paul
Joined
Dec 19, 2020
Threads
24
Messages
625
Reaction score
1,053
Location
Virginia
Car(s)
M240i, Wrangler, MB GLA 250
I run the CG Precision 5 inch catted. Because of the size it flows 20% better than other catted pipes. On e50 my car traps at 128 mph which is a good indicator of how much power it is making.
Loud?
Sponsored

 
 




Top