Whipple Stage 2, Cats, and LTHs to stay legal in my area

[GT Thunder]

I have a 24 Gt premium with Performance Package and Active Exhaust. I just had a Corsa Double H pipe and Extremes put on it.

The next thing I want to do is LTHs and down the road a stage 2 Whipple kit.

After reading on here and talking to my local shop mechanic it seems like I have two options.

First question, if I want to stay legal in my area, would the Kooks 2" High Output green catted LTHs be able to sustain a Whipple Stage 2 kit or as my mechanic told me, no cats will hold up and if I want to get the Whipple I would have to go catless and know a guy?

He told me 2" LTHs was overkill and wanted me to get some stainless works 1 7/8" that he has at his shop (I feel like he just wants me to buy from him) and to remove the cats if I Whipple it. He says it's more bang for my buck which is partially true as the Kooks headers are about 4k + tax and the Stainless Works are 2200 + tax.

Ideally I will get a Cold Air Intake when I Whipple it.

So the main question is if I can afford LTHs now, should I get the Kooks 2" to support the Whipple down the road or is my mechanic steering me true when he says keeping the cats is a mistake and they wouldn't hold up with the Whipple even if I got the High Output option, and therefore if I want to Whipple it down the road I would have to go catless and find a guy to look the other way?

Are blowing out the cats common after Whipples are added if I keep them?

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[Jonyxz]

Gesi cats are supposed to hold boosted power levels.

 

[Paul's stable]

I have a 24 Gt premium with Performance Package and Active Exhaust. I just had a Corsa Double H pipe and Extremes put on it.

The next thing I want to do is LTHs and down the road a stage 2 Whipple kit.

After reading on here and talking to my local shop mechanic it seems like I have two options.

First question, if I want to stay legal in my area, would the Kooks 2" High Output green catted LTHs be able to sustain a Whipple Stage 2 kit or as my mechanic told me, no cats will hold up and if I want to get the Whipple I would have to go catless and know a guy?

He told me 2" LTHs was overkill and wanted me to get some stainless works 1 7/8" that he has at his shop (I feel like he just wants me to buy from him) and to remove the cats if I Whipple it. He says it's more bang for my buck which is partially true as the Kooks headers are about 4k + tax and the Stainless Works are 2200 + tax.

Ideally I will get a Cold Air Intake when I Whipple it.

So the main question is if I can afford LTHs now, should I get the Kooks 2" to support the Whipple down the road or is my mechanic steering me true when he says keeping the cats is a mistake and they wouldn't hold up with the Whipple even if I got the High Output option, and therefore if I want to Whipple it down the road I would have to go catless and find a guy to look the other way?

Are blowing out the cats common after Whipples are added if I keep them?

First off the stock manifolds and cats are good to 700-800 HP 1 7/8 inch primaries are good for 800-1000 2 inch primaries good for 1000 Hp - 2500 HP just to give you ballpark figures.

 

[Q6543]

2” headers are for over 1200HP…

if you’re leaving cats on don’t waste time with headers and go stage 1.

it’s either or… either stock cats/headers and stage 1 OR off-road LTH and stage 2.

 

[Sf22giants]

If you intend to street drive the car, 1 7/8 long tubes will be more than adequate.

nothing wrong with staying legal and installing cats with the long tubes. I run Kooks 1 7/8 long tubes with no cats. When the time comes for emission, I’ll swap the connection tubes that have cats and go to the smog shop.

I also run the whipple stage 2. I can’t blow up cats since I don’t have any. Can’t say for sure that I would destroy any cats but I didn’t feel the need to chance it.

The whipple won’t work with a cold air kit so don’t waste any money on that.

 

[GT Thunder]

If you intend to street drive the car, 1 7/8 long tubes will be more than adequate.

nothing wrong with staying legal and installing cats with the long tubes. I run Kooks 1 7/8 long tubes with no cats. When the time comes for emission, I’ll swap the connection tubes that have cats and go to the smog shop.

I also run the whipple stage 2. I can’t blow up cats since I don’t have any. Can’t say for sure that I would destroy any cats but I didn’t feel the need to chance it.

The whipple won’t work with a cold air kit so don’t waste any money on that.

So do you think it would be safe to go with the 1 7/8 catted LTHs and be sustainable for a stage 1 Whipple?

It would be nice to have the extra power of a stage 2 but it sounds like a significant risk to try and run it through aftermarket cats.

Alternatively what's the worst that could happen if I run a stage 2 into catted LTHs?

If it's blowing out the cats is the only risk, would I have to buy new LTHs with cats to fix it or could I get just new cats?

 

[Q6543]

The risk is the cats clog and you blow a ringland in a piston.
The gains (if keeping cats) aren’t there to justify even doing headers. Not for under 800HP

 

[Sf22giants]

Your car will probably run fine with 1 7/8” catted long tubes on Stage 1, but I’m not a fan of that option. The tune isn’t crazy aggressive, but it’s a lot more heat than stock and lately, a few people on this forum have had Stage 1 Whipples melt their cats. Depends a lot on how you drive and what brand cats you’re running but it seems like an unnecessary risk to take when you have other options.

To answer your worst case scenario: the cat cores could melt or break apart and clog. You’d feel it when that happens, for sure. Immediate loss of power, misfires, weird fueling, a check engine light. Sometimes chunks of catalyst can blow back and damage the O2s or other parts of the exhaust. It’s not instant engine death, but I suppose that is also on the scale of worst case scenario.

On the positive side, if you blew up aftermarket cats, it’s very easy to remove and replace the cats without replacing the whole header. it’s still more money to fix an avoidable problem but easier, at least.

My personal recommendation is Kooks 1 7/8s catless on a Stage 2. Keep the catted pipes in your garage for emissions, and it keeps things simple. You can’t melt em if you ain’t got em.

 

[GT Thunder]

My personal recommendation is Kooks 1 7/8s catless on a Stage 2. Keep the catted pipes in your garage for emissions, and it keeps things simple. You can’t melt em if you ain’t got em.

The catted part of the LTHs just bolts on between the headers and h pipe and would be a quick change out for a mechanic right?

 

[robvas]

The catted part of the LTHs just bolts on between the headers and h pipe and would be a quick change out for a mechanic right?

I can switch my Kooks cats out really quick

 

[Sf22giants]

The catted part of the LTHs just bolts on between the headers and h pipe and would be a quick change out for a mechanic right?

That is exactly correct.

 

[Junkyard Dog]

The risk is the cats clog and you blow a ringland in a piston.
The gains (if keeping cats) aren’t there to justify even doing headers. Not for under 800HP

Well, he was asking about doing headers first and maybe a Whipple down the road.

GT Thunder,

There are some gains to be made with headers and a tune, so your car will be faster and feel faster and be fun to drive.

Your mechanic is correct about the 2" headers. There are also some fit issues with 2" headers that 1 and 7/8" do not have, so research carefully prior to buying.

No need to go without cats completely until you install the Whipple.

If the Whipple is way on down the road, you might as well get some horsepower increases now and enjoy driving it until then.

 

[GT Thunder]

Well, he was asking about doing headers first and maybe a Whipple down the road.

GT Thunder,

There are some gains to be made with headers and a tune, so your car will be faster and feel faster and be fun to drive.

Your mechanic is correct about the 2" headers. There are also some fit issues with 2" headers that 1 and 7/8" do not have, so research carefully prior to buying.

No need to go without cats completely until you install the Whipple.

If the Whipple is way on down the road, you might as well get some horsepower increases now and enjoy driving it until then.

I thought we could only unlock tunes with supercharger kits.

If I get some 1 7/8 headers with cats now I could also get a tune for it?

As for tuning I've been told to avoid cold air intakes on the s650s that they are a waste of money but that was when we couldn't tune them. Is it still a waste or would the CAI be replaced if I get a Whipple Stage 2 kit and be wasted money?

Some folks suggested pulling out part of the stock air filters or something AND putting in high flow filters. Do you know what that's all about?

 

[Junkyard Dog]

I thought we could only unlock tunes with supercharger kits.

If I get some 1 7/8 headers with cats now I could also get a tune for it?

As for tuning I've been told to avoid cold air intakes on the s650s that they are a waste of money but that was when we couldn't tune them. Is it still a waste or would the CAI be replaced if I get a Whipple Stage 2 kit and be wasted money?

Some folks suggested pulling out part of the stock air filters or something AND putting in high flow filters. Do you know what that's all about?

Tuning was unlocked on the S650 in August.

You can have your car tuned for whatever changes you make and change other things with the tune, as well, like transmission shifting, getting rid of the top speed limiter, raising the rpm shift points, etc.

 

[Junkyard Dog]

Here, check out other threads on the topic.

https://www.mustang7g.com/forums/threads/headers-and-tuning-2-questions.170547/

and

https://www.mustang7g.com/forums/threads/pbd-tuning-a10.171654/

and

https://www.mustang7g.com/forums/threads/cai-tune-gains.171117/

just as a few examples.

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