Spark Exhaust dB Killer Grid-O 32 mm Open 100 mm Universal G9987

Thirty-two millimetres — the narrowest Grid-O insert Spark builds, and the one to reach for when a circuit's limit is genuinely tight.

Key Features

• dB killer for Spark Grid-O silencers.
• Ø 51.5 mm outer, 32 mm internal bore, 100 mm long.
• Open type, no perforation.
• The most restrictive of the four Grid-O inserts.
• Stainless steel, removable.
• Spark part number G9987, made in Mantova, Italy.

The Bottom of the Ladder

Spark's four Grid-O inserts run 32, 38, 40 and 45 millimetres. This is the smallest, and the step down from 38 is worth about a quarter of the flow area — a real intervention rather than a trim.

Take it when the machine is well over a limit and the alternative is not riding. On a small engine it costs less than you would expect; on a large one it will be felt.

A Hundred Millimetres

Shorter than the 38 mm insert's hundred and fifty, which makes it easier to accommodate in a case with limited clear length behind the outlet. Between bore and length, bore is doing most of the work here.

The Grid-O Case

Six hundred grams of titanium with a woven mesh across the outlet, developed on the Triumph Moto2 engine. It is Spark's most extreme silencer and, unsurprisingly, the family whose owners most often need an insert.

Every Grid-O takes a 51.5 mm insert body. Only the bore differs, and that is what you order by.

Measuring Before You Order

If the silencer came to you without its insert, the outlet bore is the figure to establish. Four articles share one outer diameter and only the internal opening separates them; a photograph will not tell you which one you need.

Send us the exhaust's article number instead and we will look it up.

Fifty-One and a Half Millimetres of Body

Common to all four Grid-O inserts, which is why they cannot be told apart on a shelf. If you own more than one, mark the bore on the flange with a punch — it takes a minute and saves a wrong fitting on a trackday morning.

Legal Position

An insert manages noise; it does not create approval. On a homologated Spark exhaust the plug that came with it is the one the certificate describes, and substituting a different bore puts the machine outside the tested configuration.