So I've always wondered this, but never thought about looking it up. After the last redesign on the Grand Prix the horsepower rose in the GTP from the regular 240 all the way to 260...torque stayed the same at 280. No other (to my knowledge) GM L67'* did this. What makes for the extra 20 ponies? I figure just a reworked intake and/or exhaust manifold, maybe even a valvetrain mod, but valves/heads usually net more than 20 ponies when an automaker goes that route. Just curious as to what Pontiac did with the GTP. Also, whatever it was...is it a "bolt on" mod that can be done to other "newer" L67s? Or would it jsut be better to get more power with an aftermarket set-up of the same mod? i.e. open exhaust/performance intake

well actually the 240 to 260 jump was not with an L67 the one with 260 is an L32...

there are MANY differences from the L67 to the L32...its a drive by wire engine...so all electronic throttle and a bunch of things like that..its basically a whole new engine

From Wikipedia:

The L32 is a supercharged Series III. Introduced in 2004, the main differences between the L67 and the L32 is the L32'* electronic throttle control, slightly improved cylinder head design, and updated Eaton supercharger, the Generation 5 M90. HP output is up to 260 hp in the Grand Prix GTP, although excessive torque management in the PCM results in the 2004+ being no faster than the 1997-2003 Grand Prix GTP in stock form.


also an interesting tidbit concerning the Series II and III NAed:

The Series III motors include many changes. The intake manifold is all-aluminum on the naturally aspirated models. Electronic throttle control is added, as is returnless fuel injection. Stronger, powdered metal connecting rods are used (2004 only), instead of the cast iron style from Series II engines. Emissions are also reduced.

No. TB, intake(sc) and connecting rods. That'* about it in simple terms.

yuppers the SC that is on the L32 is a Gen V

Oh wow...and here I thought it was just a little engine tweak to make it more appealing to go along with the new skin. So is there a power difference in the NA Series III over the Series II? Thanks for the info guys...now I won't look like a noob if I ever chat with someone driving an L32.

ok..you can add the Gen V to the current L67 and expect some gains....you will need a TB adapter plate tho

and the NA version of the Series III (L26) Makes the exact same HP as the Series II (L36)