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The Best Downpipe Upgrades For The BMW M340i

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Table of Contents

Extract Untapped Potential

The BMW M340i exudes a sense of elegance, capability, and potency that’s hard to come by.

If you’re an enthusiast owner wanting to squeeze out every bit of raw power from the car, a downpipe upgrade could be your best move yet.

Aside from a remap, a downpipe upgrade arguably offers the best return on investment for power when talking about bolt-on mods. When paired with a remap, you can see gains of up to 30bhp by fitting an aftermarket downpipe.

By reducing back pressure in the exhaust system, a downpipe upgrade allows the your M340i’s B58 engine to breathe better, leading to an impressive increase in horsepower and torque.

With a reduction in turbo lag, your throttle response sees a leap in improvement. This means an instantaneous and satisfying match between your foot’s demand on the pedal and the engine’s response.

The result is a car that behaves like a more refined, powerful, and responsive version of itself, not to mention an added aggressive exhaust note.

What’s not to love?

In this guide, we’ll go over the best downpipe upgrade options on the market for your BMW M340i and some important considerations to make before jumping right in.

Catted vs Catless

When shopping for a downpipe, you will find out they come under 2 categories. 

Catted downpipes and catless downpipes.

Catted downpipes incorporate a catalytic converter, making them the road-legal option. Most catted downpipes come with a “high flow sports cat”, which are less restrictive catalytic converters that allow for improved performance while still passing emission tests.

On the other hand and usually cheaper, catless downpipes completely forego a catalytic converter.

Performance-wise, catless downpipes can give your M340i a slight edge as they allow unrestricted exhaust flow. However, they aren’t road legal and often don’t produce significant gains over a high quality catted downpipe with a high flow sports cat.

For road use, we would recommend a high quality catted downpipe that utilises a high flow sports cat to deliver maximum performance while staying on the right side of the law.

We’ll cover catted downpipes first and then catless downpipes at the end so you can make the decision for yourself. Let’s get into it!

Masata Catted Downpipe

First up on the list we have the Masata catted downpipe which is a fantastic, affordable upgrade. The 200 cell sports cat that it’s paired with also ensures your M340i remains compliant for emission tests.

When paired with a Stage 2 remap, you can see gains of 25-30bhp!

The Masata downpipe has been engineered for maximum exhaust gas flow with it’s smooth bends. It has also been crafted to deal with extreme heat that your downpipe can generate under hard driving.

Their unique flex section of the downpipe ensures that even the highest of temperatures generated won’t crack the downpipe.

MTC Catted Downpipe

Next on the list and coming in a bit pricier is the MTC catted downpipe.

The 4.5 inch bore of the piping ensures maximum flow, delivering fantastic performance and giving your M340i a deeper, more aggressive sound.

In addition the performance gains you get directly from fitting it, it also weighs a fair bit less than the OEM downpipe and catalytic converter, so you get some power-to-weight savings too!

Expect gains of 20-25bhp when paired with a remap/tune.

VRSF Super Sports Cat Downpipe

The VRSF catted downpipe is an extremely popular option among M340i enthusiasts, and for good reason!

With a gigantic 5 inch bore, this downpipe delivers impressive performance gains, and helps your turbo spool up much earlier giving you power on tap across the rev range.

Although measuring 5 inches in diameter, this downpipe can be paired with the standard cat-back section or an aftermarket cat-back section without issue.

With a tune, expect gains of 25-30bhp.

BPP Catless Downpipe

Now we’ve covered the catted options, it’s time to take a look at the catless options (decat downpipes).

First up we have the BPP downpipe.

This is a very affordable upgrade that gives the M340i great performance gains due to unrestricted exhaust flow throughout the downpipe.

The lack of catalytic converter ensures exhaust gasses can exit unimpeded, giving you increased power and torque along with a much improved throttle response.

Additionally, you can also expect a lovely, deep sound from the tailpipes alongside weight saving gains.

Since this downpipe is catless, these are sold for off road use as they won’t pass an emissions test.

VRSF Racing Catless Downpipe

The VRSF Racing catless downpipe is another fantastic option if you have your head set on a decat downpipe.

This downpipe is engineered to maximise exhaust gas flow, delivering excellent performance and a beautiful exhaust note.

The 4.5 inch bore helps relieve backpressure on the turbo, allowing it to spool earlier and get on boost quicker.

Pair it with a tune/remap, and you can see gains of 25-30bhp!


Installation isn’t too bad, and can be done within a coupe of hours on the driveway without access to a lift.

You will ideally want another person to help you, as wiggling out the stock downpipe while pushing back on the exhaust can be quite fiddly on your own. Definitely still doable yourself though if you have patience.

Once you have the stock downpipe out, fit and tighten from the turbo outwards to the exhaust instead of back the way towards the turbo. This will be the V band clamp you will want to secure first. Then you can tighten the centre bracket and exhaust clamp.

The Verdict

An upgrade downpipe for your M340i is undoubtedly one of the best value modifications you can do for increasing power, especially if you pair it with a remap.

We hope you found this guide useful at helping you choose what downpipe you should go for. A lot of it will come down to your budget and uses.

All of the downpipes in this guide will easily produce over 20bhp with a tune, so you can’t go wrong with whatever option you for.

Happy modding!