HIGH FLOW CATS...

Vettethret · 02-09-2025, 10:44 PM

Hi Fellas,

Are there any out there that actually last? From the posts I have seen on high flow cats, it seems like they fail quite a bit and aren't worth the money, any input?

SOCAL.M6.ZLE · 02-10-2025, 12:23 AM

Quote:

Originally Posted by Vettethret

Hi Fellas,

Are there any out there that actually last? From the posts I have seen on high flow cats, it seems like they fail quite a bit and aren't worth the money, any input?

Great question... if you want the good ones, look no further than the GESI UHO 4.5" #85230 rated at 850hp per cat!

I upgraded to these and had them welded in with Vbands after my American Racing HF Cats were heavily folded over after only 3k miles...

2023_ZL1-AUTO · 02-10-2025, 06:14 AM

I concur, I have a set of those as well and they are the best you can get for performance and reliability !!!

Smokin19 · 02-10-2025, 06:53 AM

Quote:

Originally Posted by SOCAL.M6.ZLE

Great question... if you want the good ones, look no further than the GESI UHO 4.5" #85230 rated at 850hp per cat!

I upgraded to these and had them welded in with Vbands after my American Racing HF Cats were heavily folded over after only 3k miles...

Exactly what happened to my AR HF Cats after 4k. Found them to be loose in the can during oil change. You could bang on them with your fist and hear them rattle. Switched to the GESI high flow 850 cats now.

JSH · 02-10-2025, 07:43 AM

My Kooks Green cats from 2020 ended up in my axleback

Vettethret · 02-10-2025, 09:39 AM

Quote:

Originally Posted by SOCAL.M6.ZLE

Great question... if you want the good ones, look no further than the GESI UHO 4.5" #85230 rated at 850hp per cat!

I upgraded to these and had them welded in with Vbands after my American Racing HF Cats were heavily folded over after only 3k miles...

Thanks guys, I will look into these now. Going in for a 2650 build in 2 weeks.

*Joshinator99* · 02-10-2025, 10:57 AM

Quote:

Originally Posted by SOCAL.M6.ZLE

Great question... if you want the good ones, look no further than the GESI UHO 4.5" #85230 rated at 850hp per cat!

I upgraded to these and had them welded in with Vbands after my American Racing HF Cats were heavily folded over after only 3k miles...

This is the way.

RobZL1 · 02-10-2025, 11:10 AM

+1 to keep the forum more active.

I've got these, too.

swisstyphoon · 02-10-2025, 03:39 PM

I also have the Gesi. They are still good after 2 years with the mods in my signature. Check out CSP Racing, they sell these Cats with headers in a kit.
Are you getting your mods done at Florida High Performance? I know Erik is a dealer for Harrop.

SWFLZL1 · 02-10-2025, 04:55 PM

Quote:

Originally Posted by Vettethret

Thanks guys, I will look into these now. Going in for a 2650 build in 2 weeks.

Let us know how the build goes, curios to who’s doing your work, I’m in SWFL also.

Vettethret · 02-10-2025, 07:27 PM

Quote:

Originally Posted by swisstyphoon

I also have the Gesi. They are still good after 2 years with the mods in my signature. Check out CSP Racing, they sell these Cats with headers in a kit.
Are you getting your mods done at Florida High Performance? I know Erik is a dealer for Harrop.

I ended up going with Powertech in St Pete. I've been dealing with Joe.

Vettethret · 02-10-2025, 07:29 PM

Quote:

Originally Posted by SWFLZL1

Let us know how the build goes, curios to who’s doing your work, I’m in SWFL also.

Powertech Performance. I don't know what Im going to do for traction. I have a K&N (Previous Owner) and a GT Haus exhaust and spin in 2nd right now with 345 R888rs.

SWFLZL1 · 02-10-2025, 08:08 PM

Quote:

Originally Posted by Vettethret

Powertech Performance. I don't know what Im going to do for traction. I have a K&N (Previous Owner) and a GT Haus exhaust and spin in 2nd right now with 345 R888rs.

Nice, I’ve talked to Joe before, seems like a great guy. I was originally going to go the 2650 route right out the gate, but decided to go with headers, Roto fab, and e to start. I also have the csp headers and high flow cats (which I think are the gesi’s) and I can tell you traction is a no go in 1st or 2nd. (I have a m6)

Curious about the harrop, he did t offer that as an option when I talked to him. Is it the same price as the Maggie, or is there other benefits over the Maggie? Haven’t heard much about them on a lt4 yet.

Vettethret · 02-12-2025, 01:59 PM

Quote:

Originally Posted by SOCAL.M6.ZLE

Great question... if you want the good ones, look no further than the GESI UHO 4.5" #85230 rated at 850hp per cat!

I upgraded to these and had them welded in with Vbands after my American Racing HF Cats were heavily folded over after only 3k miles...

Ordered! Thanks Guys.

02-09-2025, 10:44 PM	#1
Vettethret Drives: 2023 ZL1 1LE Join Date: May 2018 Location: Naples Posts: 127	HIGH FLOW CATS... Hi Fellas, Are there any out there that actually last? From the posts I have seen on high flow cats, it seems like they fail quite a bit and aren't worth the money, any input? __________________ 2023 BMW X4M Competition (Downpipes, Midpipes, Intake, Exhaust, Tune) 2023 ZL1 1LE BC Forged KXO5, 325/345 R888R, KPMF Satin Pearl Wrap, 2650/Heads/Cam/3200 stall/Meth- 918 rhwp/842 rwtq, Girodisc/Carbotech AX6, Race louvers.

02-10-2025, 06:14 AM	#3
2023_ZL1-AUTO Drives: 2023 ZL1 Join Date: Dec 2022 Location: Columbus, Ohio Posts: 1,273	I concur, I have a set of those as well and they are the best you can get for performance and reliability !!! __________________ Katech Track Day CAM 38%•BTR Dual Valve Springs-Johnson Lifters•Trend 3/8 Chromoly Pushrods• VVT Del•CNC Ported Heads•AFM Delete• C5-R Timing Chain•Katech Oil Pump•Katech 112mm•Maggie 2650 3.25” Upper & ATI SD w/10.32” +20%•10 Rib Belt•RFBG•FI Interchiller Stage 2•THPSI Port w/875cc Inj•Dual Drop In Fuel Pump•DSX Aux Pump•Stainless Works 2" w/Legend NPP Axle Back•GESI UHO 4.5" CATs•Brisk RR14S Plugs•BMR Motor Mounts•BMR Cradle Lockout/Bushings Kit•DSS Chromoly DS•RPM 8-Point Roll Cage•10lb FireSense+ w/4Fire SFI 17.1 Fire Sys•Weld Forged Vitesse Rear 17x10 Beadlocks-Front 18x6•Unlocked TCM

02-10-2025, 07:43 AM	#5
JSH Drives: '20 ZLE Join Date: Jun 2020 Location: Mile High Posts: 4,192	My Kooks Green cats from 2020 ended up in my axleback __________________ 2020 ZL1LE A10. LME LT4 390 short block, LME CID Heads, Kong E2650, FBO. 15" conversion, MT ET Street R 325/15. 100 octane: 1045hp/1055tq. 100 octane + Meth (1x10+): 1117 hp/1067 tq

02-10-2025, 03:39 PM	#9
swisstyphoon Former GM Technician Drives: 2018 ZL1 A10, 06 Silverado Duramax Join Date: Sep 2009 Location: Switzerland Posts: 402	I also have the Gesi. They are still good after 2 years with the mods in my signature. Check out CSP Racing, they sell these Cats with headers in a kit. Are you getting your mods done at Florida High Performance? I know Erik is a dealer for Harrop. __________________ 2018 Camaro ZL1 A10 Rotofab Big Gulp, Nick Williams 103, Magnuson 2650, 9.17" (14%) lower, 90mm upper, Vengeance Racing Heads (LME) Cam Package (Cammotion Stage 1), Johnson Lifters, DSX dual intank pump, Lingenfelter high flow check valve, Motion Raceworks Flex Fuel adapter, LPE Big Bore Hpfp, XDI 30% Injectors, BBK shorty headers, Custom 2.75" down pipes, Gesi Gen2 high flow cats, MM catch can. 2006 Silverado Duramax Diesel MPI Compound Turbo 40% over Injectors Efi Live DSP5 Tuning Follow me on Instagram: SwissZL1

02-10-2025, 11:10 AM	#8
RobZL1 fo'shizZL1 Drives: 2017 ZL1 Join Date: Aug 2017 Location: ATL Posts: 1,839	+1 to keep the forum more active. I've got these, too. __________________ 2017 ZL1 M6 Black \| Maggie 2650 // 103TB // Big Gulp // CSP LT's & Ultra Cats // BMR MM // BC Forged KL13 Mods being installed- oil pump, cam, ported heads, dual in-tank, Goliath and XDI, corn, etc., etc.

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