PontiacBonnevilleClub.com

No matter what you do to your Northstar, you are not going to get bang for the buck. You may add a few hp for a better exhaust of a $300 chip but the cost to bebefit ratio is very low. If you want more than 300 hp do the same thing Andrew did, build an L67 and drop it in the GXP.

The car has a decent amount of hp, but the way the PCM controls shifting doesn't ever let it get to the ground. A simple shift pattern change and less restrictive flex pipe would do wonders for this car. That's where I'm going to start, and I think everyone will be surprised how it turns out.

Shift patterns can only do so much if you have 4 obscenely long gears. My tune definitely made the car more responsive, but at the bare minimum, it needs at least one if not two gears.

On the downpipe issue, yes, that is an ugly point in the exhaust, but where will you route anything bigger, without hanging down and being at risk for snagging on something? You can't go over like most GM FWD. You'd have to route it along where the stock flat pipe is and remove it's little skid/shield.

Still curious to see how this turns out. i seen o youtube someone put a CAI on a sts..not sayingit did much but just cool to see ppl try

I had a CAI on my GXP. Made it out of spare parts, the bulk of which from from my GTO. But also other random sleeves, bends, etc, I already had. In reality, you could cobble up any intake used on Bonneville's OTHER than a GXP to a GXP. All you'd have to do is adapt it to the MAF, Secondary A.I.R. (or leave it disconnected completely), and then TB of the N*. Otherwise, the layout and holes in the body of the car are the same.

So how did the tuning turn out?

I always thought the worst problem with the GXP was the gearing was too short for the power curve of the engine. As soon as it would get moving, you could feel the timing being retarded and everything getting flat. That gearing works much better in the STS.

I just had the transmission fully rebuilt, so tuning is on hold for a while. The car is running REALLY good right now so I'm happier with it. Not sure why but it just randomly tuned itself in and pulls hard. It's faster than my GTP was in every way now. I wasn't so sure at the beginning.

techweenie wrote:I just had the transmission fully rebuilt, so tuning is on hold for a while. The car is running REALLY good right now so I'm happier with it. Not sure why but it just randomly tuned itself in and pulls hard. It's faster than my GTP was in every way now. I wasn't so sure at the beginning.

Did you have the infamous torque convertor issue? Usually these transmissions seem pretty stout.

Did you do anything special to the tranny while you were in there?

The output shaft bushing in the 3rd clutch housing burned up. It damaged the output shaft, so brand new torque converter and output shaft, all new clutches, everything but solenoids is new. I asked the shop if there was anything they could do, but there just isn't any aftermarket for this beast. It ran kinda sluggish for the first week or so after the repair, which is exactly how it was when I bought it. Then all of a sudden the stars aligned or whatever and she screams now. Right off the line it pulls very noticeably harder and truly is fun to drive now. I still get over 20mpg with her too!