High flow cat selection

[E46m3zcp]

Hey guys,

I am working on my track car and wondering if I should add high flow cats to my setup. I've got catless (Megan Racing if that matters) headers pairing down to the MagnaFlow Sport Cat-Back (16602).

To kill the stink, tame the S54 rasp, and sneak under track DB limits, I'm considering welding in cats directly into the front dual pipes of the MagnaFlow system. No burble tunes here, but it will see heavy 20-30 minute track stints, so heat is a factor to consider.

After doing some digging into what physically fits the tight center tunnel, I've narrowed it down to two options and want to see if anyone has real-world experience with either on a track car:

Option 1: MagnaFlow 59955 (2.25")

• Pros: Dirt cheap, direct 2.25" match to the Magnaflow piping, slim 4" body clears the tunnel easily.
• Cons: Heard mixed reviews about standard 200-cell metallic cores melting or hollowing out after a couple seasons of sustained track abuse.

Option 2: G-Sport / GESi HO (4" Body)

• Pros: Incredible thermal reputation; built to handle serious endurance racing EGTs.
• Cons: They don't make a dedicated 2.25" assembly. I’d have to buy the 2.5" assembly (#50022) and use step-down reducers, or buy the raw 4" core (#50002) and have my fabricator make custom end cones.
• Significantly more expensive.

My questions for the collective brain trust:

1. Has anyone run the Magnaflow 59955s on a dedicated track car? Do they actually hold up to continuous high RPMs?
2. If you went the GESi route, how painful was the fabrication/clearance given the 4" body length with reducers?
3. Any other brands I should consider?

Appreciate any insight. Cheers!

[theOracle]

I don’t have experience with the Magnaflow cats. I did run 2 different cheap cats one being Flowmaster. The cheap cats did practically nothing. The sound and stink were not improved. I bit the bullet and ordered HJS cats from Germany. Should have done this from the start. I also have the Megan racing headers. The HJS cats completely eliminated the stink and helped further eliminate rasp.

https://www.quality-tuning.eu/at/produkte/hjs/hjs-catalytic-converters

[OldRanger]

I use the Megan Racing headers with an Epic Motorsports tune on two of these cars . One has the HJS cats. I agree with theOracle that smell and sound is improved with the HJS. The smell is improved when they are warm.

I haven't tried others

[Tbonem3]

Buy the best and don't look back:

https://nam3forum.com/forums/forum/classifieds/members-parts-for-sale-wtb/e46/354995-bnib-hjs-90-95-0092-catalyst

The magnaflow HFC I had several years ago couldn't even pass smog (cat/o2 monitors)

[George Hill]

Similar boat but I am doing a 3.5" single. I was thinking I would run the Gesi (pn#10000) 4" and add a 3.5" reducer on each side. I sent them an email asking about how reliable the cat would be in this configuration for a a road race setup or if they had a better suggestion and haven't heard back.

I'll try calling them tomorrow and if I get ahold of someone will follow up.

[E46m3zcp]

A related question I forgot to ask is by how much is adding high flow cats like HFC going to reduce the dBs. From experience?

[zzyzx85]

A related question I forgot to ask is by how much is adding high flow cats like HFC going to reduce the dBs. From experience?

if i remember correctly, it affects tone mostly and volume less so