2004 Mustang GT

Better Breathing 4.6I would like to improve the performance of my '04 Mustang GT, and I'm thinking about starting with a cold-air kit and a throttle body. The car has 14,000 miles on it. Your magazine also shows many crate engines, but I'm not certain what would fit into this car. Right now I want to get the best bang for my buck with minor changes. I'm not really looking at a supercharger at the moment, but if I did, what would be your recommendation?Bob LovellMill Creek, WA

You're on the right track as far as starting with basic bolt-ons for a stock 4.6 Mustang. I can think of three manufacturers that make good-quality throttle bodies: BBK, Acccufab, and Edelbrock. All three have Web sites where you can do more research and find out where to buy their components. You can also get a throttle body from a mail-order operation like Summit (www.summitracing.com) and Brothers Performance (www.brothersperformance.com). Additionally, Accufab, C&L Performance, and BBK make intake plenums that work best when you add a larger throttle body at the same time.

Steeda, K&N, and BBK also offer good cold-air kits, which again should be available through various mail-order outfits like Summit and Brothers. Shop for price among the brands on the mail-order Web sites, but when you decide on a manufacturer, it's a good idea to stick with one brand. For example, you could do a cold-air kit and a 70mm throttle body from BBK. With the typical cold-air/throttle-body setup, expect around a 20hp gain at the wheels or around 30 at the flywheel. In any case, it'll definitely be an upgrade you'll be able to feel across the power band.

Vortech, Paxton, and ProCharger (Accessible Technologies or ATI) all make centrifugal superchargers for your car. And Kenne Bell's (pronounced "Kenny Bell") screw-type blower is also a great way to make big power. All are a good choice, and the way you go might depend on price and what superchargers the shops in your area prefer to install and tune.

With only 14,000 miles on your car, a crate engine isn't going to be a big priority for you anytime soon. But down the road, a 4.6L SOHC two-valve-per-cylinder modular V-8 is a direct replacement for your car. Several shops, including Coast High Performance (310/784-1010, www.coasthigh.com), offer stroked 4.6L short-blocks that are a direct replacement in your car. A stroker motor uses a longer stroke crank to achieve increased displacement in an engine. There are stroker 4.6s offered with as much as 310 ci in some instances, which is about 5.1 liters.

Gear NoiseIn November of last year, I purchased an '05 V-6 Mustang. I love the car, but I've been having one problem with it. When I'm cruising between 60-65 mph and I have my foot on the gas, the rearend makes a high-pitched whining noise. I took it to the dealer and they replaced the rearend. The noise was quieter, but it was still there. I took the car back in, and the service technician called Detroit to find out what to do. They basically told him they didn't know what it was, but since it didn't appear to be causing any damage, let it go and hope it would eventually break in. The technician also took another V-6 for a ride, and said it made an even louder noise at the exact same speed as mine.

I'm not sure what to do next. I love the car, but the noise is quite annoying. Any suggestions you might have would be much appreciated.Justin PrangerLabadie, MO

One idea is to take the car to a different dealership. It's possible that you'll get a better experience and better service at another dealer.

But if you've already gotten a new rearend in the car and it's quieter than before, then you might have trouble getting any further. You might have to decide what you're willing to live with. To some extent, it can be the luck of the draw in terms of what rearend you end up with. Some are whisper quiet, while others are going to have some whine in them due to the way gear lash is set. Everyone's perception is different, and one axle might be too noisy for one person, while another pair of ears hardly even notices it. But in general, I agree with you that with an essentially new car, you want it to be right.

If the rearend is too loud for you and the dealerships won't do any more to try to fix it, then you might have to spend some money either at a dealership or somewhere else to make another attempt to get it fixed.

Another option is to speak with other Mustang owners and see if they know anyone who works at a dealership, someone who is more interested in working with enthusiasts as opposed to just the average owner. Some dealers are more "enthusiast-friendly" than others. Consider getting in touch with a local Mustang club, and see if there are any other '05-'06 owners who are trying to get their cars fixed at a dealership that's more helpful than the one you've been to.