I agree; not telling them is a bad idea. Personally I would save up, build a nasty v8 drop it in and tell them you put a "8" in it. They may have to know it's a v8, but they don't have to know how much power your making
(or at least they never asked me). Other than that, turbo or NO2 is probably your best chance to get the power up and keep insurance down. I'm not sure how much boost or how much of a shot the 6 can take though. A nitrous system is pretty cheap compaired to the other options, but you have to pay for refills. In the end though I think honesty will pay off with the fact that you can drive your car and not be paranoid about getting into a accident.

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