I own a 3.4 V6 and want to have an intercooled twin turbo 5 speed 3.73 locking rear end. My goal is to reach 350 HP. I need some suggestions. Is this a good idea?

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No. Sorry but twin turbos is WAY overkill to reach 350 HP. You could easily reach your goal with a mild V8.

If you really want to go with a (single) turbo, try to find a kit where the design and fabrication is done for you. Turbos are probably the hardest to do when compared to nitrous, blowers, and V8 conversions.

your going to have trouble making a 3.4 live N/A.. they are not the toughest combinations in the world. Start with a 4.3 chevy. Its just a 350 with 2cyls lopped off.. lots of perf parts available and its got some durability.

My 1990 Nissan 300ZX has a twin turbo 3.0 litre V6 with a 5-speed and a 3.69 rear. Boost is fun. :D

You could reach your goal with a single turbo. In fact you will make more unless you go sequential on the twin turbo configuration. But even the guys with twin turbo cars are going to a single to make MORE power than that of a twin squirrel. And the reduced maintenance overall would be less....