I'm new to the Elan M100 and wish to upgrade exhaust system

[bxs]

Hmmmm.... FYI...

Over past few days I've visited several local Muffler shops and all have told me they cannot install cat-less exhaust systems per Fed Laws. However, I now understand these Fed Laws are about to change that would allow Muffler shops to install cat-less systems.

I've found a very local shop who will install my cat-less Piper exhaust for me, and he checked with EPA and all is good with this.

I not only see the Piper exhaust car-less system to be long lasting being made from SS and possibly an improved engine HP output, but also for the fact that my stock muffler system's pipes shows several areas where spot rust spots have developed over its 34 years that likely will open up to a hole in the pipe and cause me problems.

[bxs]

I pulled the rear left cover for the rear left lights, and pulled out the outside positioned dual filament bulb that is used for hazard and turn signal. The bulb was marked as 12v/32, Made in France and branded Phillips.

It's my understanding from the Owner's Handbook this bulb should be a 1157 21/5 meaning 21 watts and 5 watts. I searched for this bulb on O'Reilly and NAPA and neither had one. I then went to my trusty Volvo IPD in Portland OR and they have the correct 1157 21/5 bulb. Isn't the 1157 a US Standard bulb?

The front left single filament turn signal bulb is correct 12v & 21 watts.

My hope is that replacing the 12v/32 with a 1157 12v 21/5 my tell-tale dash indicator will become operational. Pressing the Hazard with does pulse the dash tell-tale perfectly..... it's just that the turn signals are not causing the same tell-tale dash light to flash.

[bxs]

My Piper exhaust system was shipped out from UK Aug 25, 2025 via FedEx International Priority. The tracking now shows it will deliver to me Aug 27, 2025 (today). Gosh.... that is so very fast considering it was shipped from UK to me in Seattle WA, USA. The package weighs in at around 26.46 lbs (12 KG).

Just hope the delivery does not want any import duty tax nor any tariff related fees. I suspect not, as the package is marked as not requiring signature.

BY THE WAY ...... My invoice from Piper indicated they raised their exhaust prices in April 2025 by 7%.....

[bxs]

The Piper delivered safe and sound. My local muffler shop will install it for me this coming Saturday.

[bxs]

Did I avoid or was I just lucky or was Piper fully aware of the US abandoning the "de minimis' (too small to matter") for packages arriving from overseas to US customers?

Aug 29th, 2025 was the date when the treatment of "de minimus" for small packages by US customs now required customs declarations and duties to be applied.

I sense my Piper slipped into the US a few days earlier and thus avoided the new import duties. Should I thank Piper maybe?

[bxs]

The Piper delivered safe and sound. My local muffler shop will install it for me this coming Saturday.

Well, as others here have said..... It's possible (especially considering the passing of some 34 yrs) that the nuts to be removed from the stock pre-cat can be a real bugger. My local muffler shop ran smack into this issue and ended up breaking off two of the lug bolts in their attempt to remove the nuts. So the install work has been suspended while this issue is resolved. I'm sure they will resolve this but will have to wait a day or two while they fix things for me.

Running the car without any exhaust makes the M100 sound like a Rally Car......

Photos taken at my local muffler shop... https://www.icloud.com/sharedalbum/#B2N5cQPufeqLkE

[AJSGSE1990]

However - as you are talking about a FED car, the pre-cat on your system will contain the honeycomb structure which will restrict the exhaust flow (the housing is hollow on a UK SE), so I can see why Piper are suggesting the PCE for you.

Just picking up on this, you saying that the huge cast housing in a UK SE (mine has no cat and no lambda) is empty? Just ordered the 2.25 exhaust and the engine builder was querying that part asking why do we not remove it. However if it is empty then there is no point. Looking at no more than 200bhp for the car as have been warned the gearbox is a weak point. Will run a MaxxECU and electronic throttle.

Thanks.

WhatsApp Image 2026-06-07 at 13.50.57 (5) (Small).jpeg

[dapinky]

My only qualifying caveat is that I have to assume that what you have got fitted, is either what was fitted at the factory, or an identical replacement.....

.... in which case, yes, the big cast iron dustbin is just an empty container. (which would have a honeycombe structure inside if it were an emission-controlled vehicle). The shape of it doesn't do anything for airflow as you can see it is a cylinder with a flatish bottom with a hole in it for the exhaust pipe.

It can be replaced with the PCE which is a conical shape, allowing the airflow to be smoother without the restrictions.

An alternative, would be to remove it from the car and fit some shaped obstruction to do the same job..... but it would need to cope with the high heat, so just using body filler wouldn't do it!

Realistically, it's either replace it or leave it alone - the PCE may or may not do much, but it certainly saves a fair chunk of useless weight!!!!

[AJSGSE1990]

My only qualifying caveat is that I have to assume that what you have got fitted, is either what was fitted at the factory, or an identical replacement

Ok so it may be worth checking just in case. Does somebody already make a replacement, or do I need to get another downpipe made? What scares me is just the fittings. The cast to first section of circular exhaust just won't budge after a week of soak. One I manage to get the shielding off (one bolt refuses to play) then maybe I can remove both cast and first pipe and send it to be replicated as a single 2.25 unit.

Cheers.

[dapinky]

Piper sell the PCE as a separate item, or as part of the complete exhaust system...... suitable for either the 2 1/4" or 2 1/2" exhaust pipe.

It is 'modular' and can be fitted to a standard (or other aftermarket) front pipe. They did used to sell a complete downpipe, but no longer list it on their website, so don't know if they would make one for you or not. It is always worth speaking to them on the phone, and they used to offer a 10% discount for LEC members.

https://www.piperexhausts.co.uk/product ... liminator/

[AJSGSE1990]

It is 'modular' and can be fitted to a standard (or other aftermarket) front pipe.

Right, I went ahead and ordered the PECO one from PNM a week ago. Damn.

https://www.pnmparts.co.uk/elan-m100/el ... ts-exhaust

Will the pre-cat eliminator fit to the PECO exhaust then? Going to try and get the last piece of shielding off today and see if the bolts to the honeycombe housing are in a decent condition.

Cheers.

[dapinky]

The Piper *should* fit to the Peco system (Cybox?) as the Peco was designed to fit onto the Lotus pre-cat, and the PCE is designed to fit into the same place......

...... I've never tried it, I know it should be okay, but can't comment any more than that, sorry!

[AJSGSE1990]

The Piper *should* fit to the Peco system (Cybox?) as the Peco was designed to fit onto the Lotus pre-cat, and the PCE is designed to fit into the same place......

...... I've never tried it, I know it should be okay, but can't comment any more than that, sorry!

Worth trying I suppose, two bolts sheared really close to the cast housing flange. What fun.

Thanks for the tip.

Andrew.

[dapinky]

I have yet to hear of anyone who has managed to get all 6 of the M8 bolts out of the flange without any trouble...... it is just a case of if you are lucky enough to break ones that you can get at to drill out easily or with more difficulty!!!