Spark Exhaust dB Killer Moto GP 35 mm Open 110 mm Universal G9969

The open Moto GP insert: a hundred and ten millimetres of straight-through restriction, thirty-five across the bore, in the same 57.5 mm body as its perforated sibling.

Key Features

• dB killer for Spark Moto GP silencers.
• Ø 57.5 mm outer, 35 mm internal bore, 110 mm long.
• Open type — no perforated wall.
• Stainless steel, removable.
• Not included with the Moto GP universal silencers.
• Spark part number G9969, made in Mantova, Italy.

A Hundred and Ten Millimetres

Length is what an open insert has instead of holes. Where a perforated plug breaks the gas column up at a wall, an open one works on it over a distance — and the longer that distance, the more it does.

At 110 mm this is one of the longer inserts Spark builds, which is why it manages a useful reduction without perforation.

Open or Perforated

Spark offers the choice at the same bore. G9941 has twenty-one holes and takes more noise out; this one keeps the flow freer and takes out less. Neither is the better part — they answer different questions.

On a machine already close to a limit, the open insert is often enough, and it costs less mid-range than the perforated one. On a machine well over, it will not be.

Both Sides, Same Article

Spark's Moto GP cases come in left and right versions, but the insert does not. Whatever hand the silencer is, this is the plug that goes in it.

A twin-can installation needs two, ordered as the same number twice.

Why It Is Not in the Box

Because Spark sells the Moto GP case as a racing article and most of them go on machines that run open. Making the insert an option rather than standard keeps the silencer's price honest for the people who will never fit one.

Stainless in a Titanium Case

The insert is steel even though the silencer is titanium, and that is deliberate. Two titanium surfaces sliding against each other gall; a stainless plug in a titanium bore comes out again after a season of heat cycles.

What It Does Not Do

It does not confer approval. The Moto GP universal silencer is not homologated and no insert changes that — the certificate belongs to a system on a motorcycle, not to a plug in an outlet.