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Alunox Combined Product Group Buy for Giugiaro & Stevens Esprit Turbo

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321 Stainless Steel Manifolds/Rear Systems

This is a combined product group buy for both the Giugiaro and Peter Stevens Esprit for 10 to 12 items. So if you’re looking for a new manifold or a rear system then this will count as an item on this group buy. This combined product approach should help us get the numbers more quickly if you’re interested. For those of you who haven’t seen the upgrades before, a recap on the history of the company and the product:

Alunox are an long established engineering company that supply the motorsport industry with tailor made high end exhaust systems, made of exotic materials such as Inconel, Titanium and 321 Stainless Steel etc. They also supply BAC cars with a full light weight for their current production car, the Mono.

Alunox took on the job of redesigning the original cast manifold for the 4 cylinder Esprit due to its high failure rate and short life cycle. They are direct replacements for the existing cast items.

The manifolds are made from 321 Stainless Steel, a must for turbo applications to provide a fracture proof construction. The flanges are cut out of Stainless Steel and CNC machined to give an accurate fit. The collectors use burns double slip joints to allow movement during the heat cycle accompanied by the pivoting brace mounted at the back of the head. This setup maximises the protection against shock loading.

Main Production Process Techniques:

  • TIG welding is used throughout for all for all components along with purge systems for optimum quality, giving a smooth inner surface, high corrosion resistance and complete fusion.
  • All tubes are bent using a mandrel to maintain consistent diameters and maximise flow
  • High precision dedicated jigs used throughout to maintain accuracy and product consistency.

Products on offer:

Giugiaro Full System


The wastegate is a Turbosmart compgate 40 mounted on V-Bands which is included in the manifold kit

Giugiaro Federal Full System












Stevens manifold


Both manifolds come with the fitting kit as below


The kit for the manifold includes all gaskets, stainless steel nuts and brace consisting of a fully adjustable turnbuckle for easy fitting. The downpipes are all equal length mandrel bent tubes which increase the pulse tuning effect greatly over the standard non equal length log cast configuration of the original unit. In addition to this flow is also maximized due to the smooth internal surfaces arranged to fit within the space available, unlike the rough flaking internal bores of the original. The collector is a CNC machined single piece for maximum durability and strength. It also offers an option for the Stevens Cars to run an external wastegate.

The manifold has been proven to withstand all the temperatures and conditions produced by the Esprit due to the 321 Stainless steel properties. Even at normal driving speeds the exhaust gas temperatures are typically 750 to 850 °C and greater during track use. The manifold is lighter than the original cast unit weighing only 6 Kg.  All these attributes produce a durable high quality product with proven gains in both power, torque and turbo lag reduction.
 It has been dyno tested as seen in the video below on a highly modified Esprit running at 424 BHP and 409 lb ft torque. Further gains have been made since the video was made.


Further in-depth technical info on this can be found on Dave Changes thread  


It has also been track tested and driven hard without fail. Look for feedback on the forum about performance gains.

Stevens Stainless Twin Rear System


Single Exit Rear System


Titanium Rear System for Stevens



Normal Prices

Stevens manifold £1650 + VAT.

Stevens Stainless rear system £950 + VAT same price for twin or single exit

Stevens Titanium rear system £2000 + VAT same price for twin or single exit

Giugiaro manifold and waste gate £2600 + VAT.

Giugiaro rear system £1200 + VAT.

Giugiaro federal  manifold and waste gate £2600 + VAT.

Giugiaro federal  turbo back rear system £1200 + VAT.


Note an additional link pipe will be required if you want the Alunox G car manifold to work with the existing rear system.


Group Buy Prices

These are the prices I’ve agreed with Alunox as you can see the group buy goes in stages depending on the numbers we can generate.

Alunox reserve the wright to end the group buy at their discretion.


These prices exclude VAT and do not cover fitting and shipping, I will quote separately.

Let me know if you are interested in any of the above and I can put your name down


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  • Gold FFM

1. @Gjk - Stevens manifold.

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It’s only metal, it cannot win!

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With the cost differential from Stevens to G-car, one might consider switching to an newer internal wastegate turbo on the Stevens manifold. Not the big boost/power solution, but the plumbing is simpler and 760GBP would go aways toward a modern turbo if you were thinking along those lines.

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I have had an email from Alunox confirming that the issue of the previous manifolds moving the turbo closer the rear of the engine have now been completely rectified and the fit is 100%.

It’s only metal, it cannot win!

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  • 2 weeks later...

1.  @Gjk - Stevens manifold.

2. @drscientist - G fed manifold, wastegate, turbo back 

3.  @G8nightman -  Stevens Rear System Centre Exit 

Alunox have agreed to add the Centre Exit system for the Stevens Esprit to the Product list at same price for twin or single exit






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