Spark Exhaust 60's Slip-On Pair Stainless Euro 4 Triumph Street Twin 900 (2017-2018) GTR0401IOM

Four point three kilos off a Street Twin, with papers. Spark's 60's slip-ons take the standard 7.5 kg exhaust down to 3.2, and unlike most of what Spark builds, this one carries a Euro 4 type approval issued by the Italian Ministry of Transport.

Key Features

• Pair of 60's slip-on silencers for the Triumph Street Twin 900, 2017 to 2018.
• Euro 4 homologated — approval released by the Italian Ministry of Transport.
• AISI 304 stainless steel with a Scotch-Brite finish.
• 3.2 kg against 7.5 kg standard: 4.3 kg saved.
• The lightest and shortest of Spark's three shapes for this motorcycle.
• Header pipes stay standard.

Approved, Which Is Rare Here

Most of Spark's catalogue is racing equipment sold with the plain warning that it has no road approval. This range is the exception: the Street Twin slip-ons were homologated to Euro 4 and the certificate comes from a national transport ministry rather than from a test house.

For a bike like this that changes the calculation entirely. A Street Twin is a road motorcycle, ridden to work and through villages, and an exhaust it cannot legally wear is not an upgrade.

The 60's Shape

The shortest of the three. A slim body that rises very slightly along its length and finishes with an angled slash cut rather than a square one — the outline British twins wore before anybody put a baffle in a can for legal reasons.

On a Street Twin, which is a compact motorcycle to begin with, it is the shape that keeps the tail looking short. It also ends well forward of the axle, which matters if the bike carries a rack.

Where the 4.3 Kilos Come From

Not from thin metal. The standard Street Twin silencers are large steel cans with a lot of internal chambering, because a factory has to meet a drive-by noise limit with a design that also has to be cheap. Spark meets the same limit with better material and a more expensive internal build, and the weight difference is the result.

On a 900 twin, four kilos off the back of the motorcycle is felt at walking pace in a car park before it is felt anywhere else.

Medium-Speed Gain

Spark describes the improvement as coming where it is needed, at low and medium revs. That is the honest claim for a bike of this kind — a Street Twin is not a machine anybody takes to the redline, and an exhaust that helped only at 8,000 rpm would be helping nowhere useful.

Installation

Slip-on level: the standard silencers come off and Spark's go on, header pipes untouched. The approval covers the exhaust as delivered, so nothing about the fitting is a compromise on the paperwork.

Fitment & Compatibility

Triumph Street Twin 900, 2017 and 2018. The black ceramic version of this pair is GTR0401BOM. Spark's other two shapes for the same motorcycle are the Trumpet, GTR0402IOM and GTR0402BOM, and the Sinfonia, GTR0403IOM and GTR0403BOM.

Road Approval

Euro 4 homologated. Spark lists the article as approved and states that the approval was released by the Italian Ministry of Transport.

Specifications

• Part number: GTR0401IOM
• Type: Slip-on, pair
• Design: 60's
• Material: AISI 304 stainless steel, Scotch-Brite finish
• Weight: 3.2 kg (standard 7.5 kg)
• Road approval: Euro 4 homologated
• Fitment: Triumph Street Twin 900 (2017-2018)
• Manufacturer: Spark Exhaust Technology, Mantova, Italy