performance advantage to going catless at section 1 (full supersprint setup)?

[simonnim]

it doesn't, technically everything that isn't the OE USDM headers/cats is illegal in California, outside of that you're rolling the dice with the risk getting higher in the following order

euro headers/euro cats - negligible increase in smell/pollution, OE part so would only raise red flags to a smog tech that is knowledgeable on the E46 M3 us/euro platform differences
Gesi/HJS cats - negligible increase in smell/pollution, but does not look OE, more likely to get spotted by a smog tech if they go looking
generic sport cats - likely higher smell/pollution, the smell alone will be setting off red flags

Thanks for the answer. I'm not that knowledgeable about hi-flow cats and the like in California. I've heard people passing and was just curious if hjs was legally able to pass in California. I know you can just find a shop that doesn't really inspect, but the few I've gone to have begun to inspect more.

I Guess I'll just stay stock until I leave California some day.

[TosM3]

quick question I have supersprint 63.5mm Stepped Headers with 63.5mm HJS Catted Section 1. Would I lose power from using a HJS catted section one vs non catted?
I'm trying to sale my catted section 1 but if I wont lose power I will just keep it.

[Syfon]

A friend & I had our cars tuned at the same time. Very similar mods across the board, albeit he had twin 100cell cats, mine has none.

His made more torque (~10nm) in the mid-range, mine made more torque & hp (~10-15nm & hp) right up top.

So yes, there is a performance gain to be had going catless, although it is minimal.

[Slideways]

quick question I have supersprint 63.5mm Stepped Headers with 63.5mm HJS Catted Section 1. Would I lose power from using a HJS catted section one vs non catted?
I'm trying to sale my catted section 1 but if I wont lose power I will just keep it.

The car is unpleasant to drive without a catted setup. The car will smell of fuel like an old boat. The power loss or gain, being extremely minimal, shouldn't matter.

[TosM3]

The car is unpleasant to drive without a catted setup. The car will smell of fuel like an old boat. The power loss or gain, being extremely minimal, shouldn't matter.

I understand that but this isnt my daily. But I was curious to see if I will lose a good amount of power.

[Tbonem3]

I was always able to feel the change in responsiveness (not so much the actual hp and or tq or where in the powerband it had changed) when I went back and forth between catted/catless but am very happy to say that I couldn't tell the difference this time when I fitted the SS hjs sect 1! Smell at cold was like the euro setup (slightly stickier than u.s), but just like stock once warm.

I think hjs sect 1 doesnt give anything up to catless. They say it flows like 95% the same or something. This is 200 cell. SS's other, non e46 m3, cats are 100 cell.

[Tbonem3]

quick question I have supersprint 63.5mm Stepped Headers with 63.5mm HJS Catted Section 1. Would I lose power from using a HJS catted section one vs non catted?
I'm trying to sale my catted section 1 but if I wont lose power I will just keep it.

Like I put above, keep it! I know it's a lot of $, but nothing's better. You get the gains of catless with the conscience of factory pollutant clean up.

[Slideways]

I understand that but this isnt my daily. But I was curious to see if I will lose a good amount of power.

Even if it is not you daily or it lost 3% hp or torque, it's still not worth it for multiple reasons more important than the power gain/loss.

[RazorM]

Do you guys think that for Euro car with euro catted section 1 is worth considering performance wise to instal HJS cats? Since I will be doing remap with Hassan and I want to have best possible setup for the money. But I can’t stand decat smell and sound.
And also, the cats on my car are 22years old/ 140000miles. I have no idea how much the age can impact its ability to flow. They still pass emissions though

[Slideways]

Do you guys think that for Euro car with euro catted section 1 is worth considering performance wise to instal HJS cats? Since I will be doing remap with Hassan and I want to have best possible setup for the money. But I can’t stand decat smell and sound.
And also, the cats on my car are 22years old/ 140000miles. I have no idea how much the age can impact its ability to flow. They still pass emissions though

You'd have to get it on a dyno and measure the exhaust with a wideband sensor. If it makes the power, passes emissions and the ECU is not throwing a code, they are probably still fine. If there is an issue, then replacing the stock cats with a pair of HJS on the stock euro section 1 would be the way to go.

[PSUEng]

Do you guys think that for Euro car with euro catted section 1 is worth considering performance wise to instal HJS cats? Since I will be doing remap with Hassan and I want to have best possible setup for the money. But I can’t stand decat smell and sound.
And also, the cats on my car are 22years old/ 140000miles. I have no idea how much the age can impact its ability to flow. They still pass emissions though

Interesting your cats lasted that long. On my car (US) they lasted to like 80k. I hypothesize that the location on the US cars is detrimental to them, and friend of mine with an E36 M3 had same problem years ago. Anyway, I replaced them with full SS V1 system with HJS section 1 and after a few hundred miles of break in and a remote session with Hassan, the car runs amazing.

[RazorM]

You'd have to get it on a dyno and measure the exhaust with a wideband sensor. If it makes the power, passes emissions and the ECU is not throwing a code, they are probably still fine. If there is an issue, then replacing the stock cats with a pair of HJS on the stock euro section 1 would be the way to go.

I had car on dyno, they use AFR sensors attached to exhaust tips. Attaching the results. Hard to say what means “if it makes the power”. The top end is kind of mellow though. It can mean many things I guess, also some restriction on cats.
Numbers are nothing to write home about I think, MAHA dyno is reading generally lesser numbers compared to dynojet.
There are workshops where they clean dpf filters and catalytic converters. I have no idea if it’s worth it, it’s like 150€. but I know they also flow test them before/after.
What I was mostly curious is whether there are some gains on the table by installing HJS in comparison to euro cats.

[Obioban]

Interesting your cats lasted that long. On my car (US) they lasted to like 80k. I hypothesize that the location on the US cars is detrimental to them, and friend of mine with an E36 M3 had same problem years ago. Anyway, I replaced them with full SS V1 system with HJS section 1 and after a few hundred miles of break in and a remote session with Hassan, the car runs amazing.

I fried my first set of US cats at less than 60,000 miles. Stock US location plus track heat levels is not a recipe for longevity.

My SS/HJS cat's have probably 30X the track miles my stock US ones did when they failed, with no issues. Nice reliability upgrade!