"This journal entry is part of a Special Series on improving the heavy, restricted and weird sounding E46 M3 stock exhaust system with Supersprint's 63.5mm performance exhaust.
This journal entry covers the unboxing of my E46 M3 Supersprint complete exhaust - the great, the good, the bad, and in-depth look at what makes this special. "
My current exhaust.
Back in April 2022, I launched the Part Deux Group Buy for E46 M3 Supersprint exhaust systems. The backstory to both group buys are here. One of my main motivation this time around was pretty evident: I now owned an E46 M3 myself!
Unfortunately the previous owner didn't exactly leave it in proper mechanical condition. Relevant to this journal entry is the exhaust: my car came fitted with a header-back Magnaflow exhaust.
Not a bad kit at all for sound and price - but it isn't the greatest this legendary chassis had in terms of exhaust design and development.
All the juice with none of the sugar.
Reviewing my configuration.
In my initial Supersprint journal entry, I stated my E46 M3 is a Sunday driver.
It needs to be fun to drive with friends & family.
I was unwilling to sacrifice in smell and noise for performance. Ever more so considering I'm fitting a CSL airbox along with.
I want to experience the S54 induction noise glory for myself.
I was set on going with the "Complete Catted Sport Kit"
- 63.5mm Headers
- 63.5mm HJS Catted Section 1
- 63.5mm Resonated Section 2
- Sport Rear Muffler
A small, but heavy change.
After discussing with a few perennial E46 M3 owners with whom I share similar sound tolerances and goals, I decided to switch my rear section selection.
I opted for the EC/TUV Approved, road legal "Strada" / Street rear section.
It's essentially an OEM box with straight through internals. It's just as big and I'm guessing just as heavy.
This is no Akrapovic titanium exhaust.
Here it is.
The tips are chromed if I'm not mistaken. The slanted design really suits the E46's rear diffuser curvature.
The rear section is designed to fit OEM section 2 or equivalent aftermarket options. They also fix a common issue on these e46: disintegrating muffler flanges.
Each Supersprint products, except the headers, usually have a plaque indicating it's SKU, production batch and other serial information.
The headers & catalytic converters are the crown jewels of this kit and why we spend the money we do with Italians.
They know where quality matters.
The legendary headers.
Supersprint famously introduced enlarged, stepped design headers to the S54 engine over a decade ago.
There are somewhat precise formulas to determine the diameters, and the position at which the increase in primary diameter should be.
Stepped designs are suited for precise applications such as high compression, high RPM engines, short primary header lengths, long duration cam with lots of overlap and early exhaust valve opening events.
This is where Supersprint spent the R&D and manufacturing budget.
These are truly works of arts. It brought me back to feelings of unboxing my V10 headers.
You can visibly see the step in primary runner diameter.
Pay attention to the welds: the headers are TIG welded.
The Italian signature.
Proper flange work.
The headers are designed with all 02 bungs in their proper positions.
The merge collector diameter is enlarged to 63.5mm for optimal performance. As such, this is a slip fit designed specifically for use with Supersprint's selection of section 1 pipes.
HJS Motorsport Catalytic Converters.
HJS needs to be properly introduced. We often hear the 3 lettered company thrown around as gospel by enthusiasts.
Let's see why.
German developed and made.
HJS is a German catalytic converter development and manufacturing company. They have been developing their Motorsport products for over 30 years working with various OEM race teams.
FIA / WRC Homologated.
The HJS Motorsports products themselves are their premium products developed to endure the higher requirements of motorsport applications by meeting FIA homologations standards.
From my research, I believe Supersprint uses a variant of the HJS Motorsport CUP lineup. The CUP lineup is their entry level Motorsport grade product.
High Flow and High Durability.
They use a stainless steel catalyst with a 100 CPSI for optimized gas flow. They are rated up to 950C and are suited for non-turbocharged production engines.
The HJS cats have metal internals for supreme durability at the higher temperature ranges of motorsports.
Supersprint positioned the cats much further downstream than BMW which fitted the cats straight on the headers for US cars. This helps reduce operating temperatures of the cats and prolongs their life.
The HJS Motorsport CUP cats have triple foil winding, and three winding centers. You can read more about it here.
If a member can trace the number to confirm the product lineup used - I'm all ears.
The HJS Motorsport cats come in a few select diameters. You can see Supersprint tapers down the diameter to suit the 63.5mm piping.
The section 1 piping comes fitted with the required pre-cat 02 sensor bungs as well as post cat bungs fitted directly to the HJS units.
The 63.5mm section 1s, whether they are catted or not, all come with flanges to fit the OEM section 2 or equivalent aftermarket section.
"Heat is expensive to manage, and it gets more expensive to manage reliably. Having an entry level motorsport product is re-assuring for long term reliability and knowing I'm getting the most performance out of my S54 without pushing unfiltered exhaust emissions into the atmosphere."
The Section 2.
Tuning and power levels achieved by naturally aspirated S54s have drastically increased throughout the years thanks to breakthroughs in engine tuning and cams.
This led to new engine performance bottlenecks being found.
Obioban at NAM3 famously isolated the initial single tube diameter as the main issue.
Supersprint initially developed a 60mm single tube section 2 for the E46 M3.
The E46 M3 underbody is a limiting factor in its exhaust development, they couldn't revise the single tube design with a larger diameter.
The 63.5mm Twin Tube version.
Obioban got with Supersprint to develop a new version with a larger overall piping diameter.
The results are a system that can support power levels up to 400whp.
This version is a twin-tube design to achieve the required diameter targets within the packaging restrictions of the underbody. This section is available in resonated or non-resonated variant.
This is the resonated version which helps keeps the decibel levels and rasp down.
The section 2 has flanges to mount to the Supersprint section 1 or the OEM equivalent.
They also fitted flanges to be bolted to the rear section or OEM equivalent. They provide a loose flange to be slid on the left pipe pictured below.
Notice the tapered section - the sliding flange most likely acts as an heat expansion feature.
It comes fitted with welded studs to properly fit the underbody.
The section 2 is where Supersprint starts loosening its standards a bit. They use MIG welding techniques.
It's faster and cheaper - but doesn't look as good. The rear sections are MIG welded as well.
The section 2 comes with Supersprint specific hardware as it is a twin-tube design that differs from OEM.
As a rule of thumb with Supersprint, if it uses the OEM routing, source your own hardware.
"Just like Germans, Italians have their own peculiar ways of doing things."
My title was definitely tongue-in-cheek being of Italian descent myself - yet there's some truth to it.
Italians are notoriously slow to manufacture goods; quality they'll say, and for the most part they are right.
Yet there often remains irrational things about the overall process of Italian manufacturing.
Let's cut to the chase: my rear section's canister came dented like a winter beater parked downtown with no care given - and one of the tip is dented.
The tip's dent is difficult to catch with so much light, and the polished & chromed metal. It's the inner tip below.
Why, why Supersprint believes shipping its exhausts in paper thin cardboard boxes is OK still boggles my mind.
Supersprint uses thick plastic bags that are shrink wrapped around each component to further protect them.
They also add smaller, still paper thin cardboard boxes and a form of stretchable padded cardboard to what they perceived are sensitive areas like tips, flanges etc.
Lastly, Supersprint doesn't include hardware on most of their kits. On my configuration, only the section 2 came with the extra flange, bolts, washers and nuts to install it.
...they taped them to the inside of the vacuumed plastic bag. Half of them were flying around inside the package, good thing the bag didn't get cut.
"Here's the bottom line: it's good, but not good enough. Somebody needs to fix this."
If they'll ever read this, my recommendation to them would be...
Be like Mike, be like Nike: add "Air" cushions, and foam, a lot more foam.
All of my packages were inspected by customs. As such, needed to be opened to be inspected.
Did this influence the final dents on the rear section?
Partly, I'm sure.
I can only suspect an Italian business shipping big packages to another Italian is a red flag.
I kid I kid.
Good intentions, bad results.
My situation was different than what I expect members to experience.
I wanted to get my system pronto to document the unboxing and installation.
It wasn't repackaged by MPower.
Speed has risks - this is not all on Supersprint.
The replacement experience."