Gransport - Euro or US manifolds?

rockits

Member
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6,218
My 4200 has only just ticked over 15k miles so expect the primaries are working pretty well. Maybe could make a difference and why I have had no issues.
 

JonW

Member
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2,333
I have US spec manifolds, Supersprint decats in place of the secondary cat, unsilenced X pipe and stock GS rear boxes. The car is loud when in sport mode but not obnoxiously so, out of sport mode I would say its around as loud as the stock exhaust is in sport mode. There are of course more snaps and pops between gears. There is a small amount of drone in sport mode when cruising, never really bothers me and its easily suppressed by reverting to normal mode. Generally it seems a good compromise, particularly if you want to keep the "gentle V8 rumble" when not pressing on.

On the subject of MOT's in my experience you will need sports cats (such as the Larini ones you mention) in place of the secondary cats. My car has both narrowly passed and narrowly failed on emissions with the secondaries totally removed. Needless to say removing the decats and refitting the stock secondary cats each year is a little frustrating. I know other cars pass no problem with this configuration however. Maybe my primary cats are not operating at peak efficiency any more?
Really helpful response and great example of why this forum is so great!
 

JonW

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Enquiry form submitted to Larini requesting lead times (as not currently in stock!)
 

DaveT

Centenary Club
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2,147
Would this still release plenty of noise and help the engine to breathe better, even though there would still be one OEM catalytic converter in the manifolds?

If I did this, it would mean I had US spec manifold, Larini sports cats, an unsilenced H-pipe, and stock GS valved back boxes. Any on here with experience of what this would sound like?

I’m hoping this means the car could be nice and noisy when I want it to, but still be able to take it out of Sport and reduce the volume to a gentle V8 rumble.. It also means I could return the car to completely stock should I decide to sell.
Jon

Pretty sure this was the set up i had in my GS Spyder now owned by Mr Pea.
It was just perfect for me. Not too OTT but under load it sounded fantastic.

Stevie?
 

JonW

Member
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2,333
Impressively, have got a response from Larini already. Even more impressively, they are close to trying to persuade me to spend less money with them!....

Thank you for your e-mail. We can offer you for your GS with the '2 headers cats/2 cat' oem set-up:


Maserati GranSport, Larini Secondary ‘Sports’ Cats = £1678.31 plus Vat = £2013.97 ... 42 days eta

Maserati GranSport, Larini Secondary ‘De-Cat’ Pipes = £974.96 plus Vat = £1169.95 ... 14-21 days eta

Delivery = + £25.00 plus Vat = £30.00

As you may order directly from us, I can waive the delivery charge, if ordered within 2 days.

To order: https://www.larinisystems.com/information/order-form

A guide:

If you wish to increase the richness of the GranSport’s sound we recommend the replacement of the secondary OE secondary catalyst sections with the Larini Secondary ‘De-Cat’ Pipes. The car has a set of primary cats up in the manifolds and a set of secondary cats fitted downstream. The standard secondary cat sections are hugely restrictive. The OE pipework is crushed massively in sections and the cats are quite restrictive and prone to failure. Many owners fit this Larini part, as the power, torque and sound gain is significant! …Yet the primary cats are retained ensuring no check lights on the dash etc.

If you’re mindful however of removing catalyst equipment from your car I recommend you go with our secondary ‘Sports Cats’ sections. Our metallic sports cats are vastly superior to the bulky ceramic original items, registering similar emissions outputs with even better sound & power!

If you have any questions please do let me know.
 

Evo Cymru

Junior Member
Messages
534
I have US spec manifolds, Supersprint decats in place of the secondary cat, unsilenced X pipe and stock GS rear boxes. The car is loud when in sport mode but not obnoxiously so, out of sport mode I would say its around as loud as the stock exhaust is in sport mode. There are of course more snaps and pops between gears. There is a small amount of drone in sport mode when cruising, never really bothers me and its easily suppressed by reverting to normal mode. Generally it seems a good compromise, particularly if you want to keep the "gentle V8 rumble" when not pressing on.

On the subject of MOT's in my experience you will need sports cats (such as the Larini ones you mention) in place of the secondary cats. My car has both narrowly passed and narrowly failed on emissions with the secondaries totally removed. Needless to say removing the decats and refitting the stock secondary cats each year is a little frustrating. I know other cars pass no problem with this configuration however. Maybe my primary cats are not operating at peak efficiency any more?
This is pretty similar to mine too - reminds me that I need to pop up to the local grage to see how close to the emissions limit it is before the MOT is due!

Would concur with the noise level - seems just about right to me, noticeable in sports mode even with windows up but not badly so and can put it 'stealth' mode/out of sport if needed. I went for the secondary cat delete option as I got some for reasonable money and it seemed easier than faffing about with the primary pipes. Like the idea that if the primary cats do fail now they should just shoot out the back!
 

JonW

Member
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2,333
Decision made...

Car is now booked in to Emblem towards the end of September for an underbody waxoyl treatment (final item on my original Emblem list!) and the fitting of some decat race pipes!
 

rockits

Member
Messages
6,218
Excellent.....good work Jon. I am sure it will sound epic but also be balanced as well. I hope so!
 

JonW

Member
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2,333
Another update - which may or may not be useful for other forum members in the future.

Before I placed my order for the de-cat pipes, I contacted Larini, and asked them the following:

Two quick questions if I may:

1) if I went with the de-cat pipes, do you know whether the removal of the secondary cats would lead to emissions failure from an MOT perspective? I understand that all the lambdas are in the primary cats, so no check engine lights, but I’m presuming the secondary cats are there for a reason?

2) is there a reason why on your website it says the de-cat pipes are for off-road use only? I would understand that if they were being fitted to a car with no catalytic converter, but am unclear why this is given they are designed for a car with the US spec manifold with built in cat....

Below is their response:

Hi Jon,

No problem.

1) In the UK you need one set of functioning cats fitted by law, which you have in the manifolds. The primary cats will see you through the MOT, for emissions too - provided they haven't fallen apart (which is rare on the primary cats, but could happen if the car backfires badly for example). The secondary cats were designed for the emission strict regions like California and Switzerland, but found their way on to other GS's presumably due to economies of scale and availability. I have seen both manifold/cat types on UK GS's and it seems to be a bit of a lottery regards whats fitted, bizarrely.

(FYI, it's not shown on our website but our secondary sports cats are fitted with lambda ports and blanks, so if your primary cats did ever fall apart you can move the probes downstream to the Larini cats to pick up a reading).

2) Emissions requirements vary from country to country and in the USA from state to state, where sometimes any removal of factory fit emissions equipment is illegal. Hence we simply add that line as a disclaimer and a warning to the customer to check their local state controls before purchasing.

Hope that helps.
 

TimR

Member
Messages
1,155
You know what would be a real help would be to report the numbers on the emissions sheet from the last MOT ( which Im assuming it passed! )
Being able to compare the before and after would be most instructive in terms of the efficacy of the secondary cats., and to some extent where the limit threshold is if you were to get a fail...
 

JonW

Member
Messages
2,333
You know what would be a real help would be to report the numbers on the emissions sheet from the last MOT ( which Im assuming it passed! )
Being able to compare the before and after would be most instructive in terms of the efficacy of the secondary cats., and to some extent where the limit threshold is if you were to get a fail...
Good idea - will see if I can find my last emissions sheet, or will try and have it measured before and after I take off the secondary cats...
 

Mr S

Member
Messages
260
Me and Zep swapped over my US spec headers for Euro spec headers, and fitted Larini sports cats, and i also then fitted a Benny X pipe. I did initially think about the modded rear boxes, but the car is already borderline for me in Sport mode, but does sound ace. Larini were a great company to deal with, so glad you are finding the same thing. No idea on emissions, but maybe do similar to others and get it looked at before the MOT just to makesure.
 

JonW

Member
Messages
2,333
Me and Zep swapped over my US spec headers for Euro spec headers, and fitted Larini sports cats, and i also then fitted a Benny X pipe. I did initially think about the modded rear boxes, but the car is already borderline for me in Sport mode, but does sound ace. Larini were a great company to deal with, so glad you are finding the same thing. No idea on emissions, but maybe do similar to others and get it looked at before the MOT just to makesure.
Thanks - did you manage to sell your Larini H-pipe?
 

JonW

Member
Messages
2,333
Nope, still got it, along with the screamer pipes i had fitted. (Decat secondarys)
So you basically had the set up I’m going to have?

I’ve just ordered the decat race pipes from Larini, and have a forum special H-pipe on the car....
 

Mr S

Member
Messages
260
Sounds like it yes. Car sounded good, but now sounds much better. However, the cost and effort involved was considerably more.
 

JonW

Member
Messages
2,333
Sounds like it yes. Car sounded good, but now sounds much better. However, the cost and effort involved was considerably more.
What made you decide to switch out the manifold? Were you having problems with the cats?

I’m 1/2 tempted by your Larini H-pipe, but think I need to wait and see how mine sounds with the decat pipes and unbranded h-pipe... I’m also still unsure whether I will eventually switch over to an x-pipe
 

TimR

Member
Messages
1,155
I might be in the market for your secondary decat screamers if they're up for sale ?
 

Zep

Moderator
Messages
3,154
I might be in the market for your secondary decat screamers if they're up for sale ?
You will like them, the fab work is very nice and the squish section is one of the best looking solutions I have seen.