No matter how much you pay it is going to crack. I spoke with a company that makes manifolds for the evo and srt-4, and now has a Camaro SS TT kit. They said they no longer use anything but cast iron prior to the turbo because tubular manifolds always crack and often soon enough to piss off customers.
Subaru's have unequal length runners because the engine is a boxer (think a V4 with a 180 degree V angle). They can't put the turbo on the top or bottom of the engine, so the runners are unequal length. The boxer itself is just as much a part of the subaru sound as the runners.
On a turbocharged vehicle, the less metal and air between the engine and turbo, the better. You want as little exhaust energy as possible being wasted as heat before going through the turbo and spinning the turbine. Purposely making long runners doesn't make a lot of sense.
You also want a consistent flow of air on the turbine vanes, and this is why you wan them as equal in length as possible. Twin scroll turbos separate the odd and even cylinders to minimize interference and maximize scavenging, but AFAIK, there isn't such a thing as a twin scroll T25.
Subaru's have unequal length runners because the engine is a boxer (think a V4 with a 180 degree V angle). They can't put the turbo on the top or bottom of the engine, so the runners are unequal length. The boxer itself is just as much a part of the subaru sound as the runners.
On a turbocharged vehicle, the less metal and air between the engine and turbo, the better. You want as little exhaust energy as possible being wasted as heat before going through the turbo and spinning the turbine. Purposely making long runners doesn't make a lot of sense.
You also want a consistent flow of air on the turbine vanes, and this is why you wan them as equal in length as possible. Twin scroll turbos separate the odd and even cylinders to minimize interference and maximize scavenging, but AFAIK, there isn't such a thing as a twin scroll T25.
