A twin-cam six-cylinder engine raised horsepower to 189.

The engine in the EX has variable valve timing, which improves the torque, or getaway response, and raises horsepower to 127.

Though this had not raised horsepower, which was still 35, it did improve torque and responsiveness.

As a result, the designers say, the electronic muffler would raise horsepower by as much as 7 percent and increase fuel efficiency.

That helped to raise horsepower to 283 - the first time an American manufacturer had been able to achieve one horsepower for each cubic inch of displacement, the company said.

But the turbo raises horsepower to 222 and provides straight-line torque of 221 foot-pounds through the engine's usable range of revs.

Modifications have raised horsepower by 37 from last year, to 227; the I30's engine was tweaked to produce 5 horses more than the Maxima's.

It was switched over to multi-port fuel injection in 1988 which raised horsepower to 95.

G.M.'s tried-and-true 3.8-liter V-6 provides power; in the Ultra, a supercharger raises horsepower to 240, from 205.

The Ultra's supercharger raises horsepower to 240, compared with 205 in the basic Park Avenue.