[Dangerous Dave]

I've got flowtech equal lengths and I don't have any trouble with changing plugs-however I bought the car with them on already-I've had all 3 different kinds. Unless your racing in a class that does not allow longtube headers-why limit yourself? Longtubes will flow better than shorties equal or unequal, and that way you can make more mods before having to step up to big headers-like stated above-with a stroker or 351 or something. Longtubes are definitely the best way to go-If you're looking to buy new. If your buying used-then you'll come across equal length shorties for $50-$75 and an off-road h-pipe for $50-$75, then for $150 or less you have a free flowing exhaust that you'd be able to sell for the same price you bought it for if you decide to build a motor too big for that set-up. The one reason starting off with a stock Mustang-I'd end up with shorties 9 times out of 10.