I don't know what good gas milage means to you... verybody has a different opinion on this one.
If you are putting more Cubic feet of air then you will have to balance it with the right amount of fuel, generally 14.7:1 is prefer. That's 14.7 of air to 1 fuel.
If you really want the accel and you don't drive at 180km/hr. There is a really cheap way of increasing torque with out the stroker. Try getting a bigger Ring and pinion set, lower you gear ratio. Your rev would be normally higher than before, but no worry, your engine is working less than before. This will give you the accel you need at a relatively lower price.
If you get someone to do it for you make sure that they are differential experts. Ask then you write down the "runout" and "backlash" so you can have record of it. These numbers will determine if they did it right and how long your diff. will last.
You must also correct your speedometer... your top speed will top put your acceleration is much faster.
An example: Try taking off in 1st and 2nd gear, which is faster? Lower is gears is like taking off in first.