When I bought the car it came prefitted with hardpipes and a Forge recirculating dump valve. This was a nice subtle sound for everyday use, easily audible within the cabin on gearchanges. However with the Evo now relegated to weekend duties for the most part I thought I’d try ‘chav it up’ a little but buying a Turbosmart Dual Port Blow Off Valve. This dump valve, as they are known, has two ports to allow some air to recirculate back into the intake and some to be released out.
Fitting in my case was very easy; Simply remove the Forge valve by undoing the jubilee clips securing it to the intake pipe and replace with the Turbosmart.
The Turbosmart has a hardness setting that is easily adjustable. By twisting the case you can specify how much air gets released to atmosphere and how much gets recirculated into the intake system. Too ‘hard’ and the engine could stall at low revs by venting all air out, too soft and all the air gets recirculated.
After a trial run down the road, at a mid range setting, the car sounded great, with no stalling issues and had my brother in the following car chuckling at the commotion on each gear change. The hiss of escaping air is now clearly audible outside the car and as juvenile as it is, I think it’s great!