PontiacBonnevilleClub.com

Hey what's up everybody!
New guy from New Mexico!
I just bought an 05 GXP (2-3 Days ago). I'm new to Bonnevilles, Northstars, and of course, the community.
I got a lot of questions regarding performance mods!

Before having the GXP, I used to own two w-body. (05 GP GTP, 04 GP GTP Comp G.)
The mods were the usual, Pulley, tune, exhaust blah blah blah...
And now, since I got the Bonneville, I want to know how easy or hard is it to mod it? or if there is any mods at all.

I was just thinking to do some bolt on's like better exhaust flow, lower temp plugs and t-stat, thicker wires, a tune, intake, gears, etc... (if possible)

So what you guys think? Any input would be awesome!

Oh and ill upload some pics!!

You aren't going to gain much doing exhaust work. It's more an auditory preferance than anything.

Otherwise, there isn't much out there for this car and the N* V8. You're left to scavenge the Hi-po parts bins for regular (SSEi) Bonneville's, FWD Cadillac STS's that share the platform, and W-Body's and "custom engineering" things.

The PCM can be tuned now, I just don't remember who the tuner is...

Uff... how about headers??

and "custom engineering" things?

Like what?
Intake? A Downpipe?

Oh also, any free mods that could be done to the GXP?


And I heard that madtuner makes a tune for this cars... But have anyone tried it?

Yea, that is the tuner I believe, one or two here run it but I don't know if they come around much. There is no headers available, the way the exhaust runs under the oil pan kills that idea unfortunately. There is just very little room under the hood in general so intake and exhaust are pretty restricted.

Ohh nice!
Gotta chase them down and ask 'em lol

And well, I came from the L32 and they love the cold, how about the LD8?

I'm asking because, like I said before, I'm planning on running a colder t-stat(180* or 160*) and colder plugs. Have anyone tried this?

Oh btw, thanks for the input so far!

The fellow New Mexican welcomes you! What neck of the woods you in?

Welcome to the club. There is not too much you can do to make more power. The engine makes its power and torque at the higher RPM's unlike the L67 (supercharged 3800) I know there is a madtuner canned tune that may give you 3-5 extra hp. But is it worth $325? You can't run headers because there is no ground clearance, and the engine is already a 32 valve high performance engine that you are not going to find any internal mods for like hotter camshafts etc. I'm not sure running a cooler t-stat is going to make that much difference but if you do don't go down to 160 as you may end up with diagnostic trouble codes and the temperature that the fans turn on also has to be changed. You can replace the factory intake wit a CAI but I do not know how much that will help. Most of the club members decide that if they want an engine to mod, to get the L67 instead. So most of the mods you see on the GXP's are cosmetic.

RJolly87 wrote:The fellow New Mexican welcomes you! What neck of the woods you in?

Hey thanks!
And I live in Santa Fe.

bobgto65 wrote:Welcome to the club. There is not too much you can do to make more power. The engine makes its power and torque at the higher RPM's unlike the L67 (supercharged 3800) I know there is a madtuner canned tune that may give you 3-5 extra hp. But is it worth $325? You can't run headers because there is no ground clearance, and the engine is already a 32 valve high performance engine that you are not going to find any internal mods for like hotter camshafts etc. I'm not sure running a cooler t-stat is going to make that much difference but if you do don't go down to 160 as you may end up with diagnostic trouble codes and the temperature that the fans turn on also has to be changed. You can replace the factory intake wit a CAI but I do not know how much that will help. Most of the club members decide that if they want an engine to mod, to get the L67 instead. So most of the mods you see on the GXP's are cosmetic.

Thank you, thank you!

Oh, I see... Seems that we are handcuffed with performance....
Well how about NOS (NAAWWZZZ lol)?
Have anybody tried to bottle their gxp?

And now that you talk cosmetic mods... Any chance with a ram air hood for this cars?
That would be awesome!

When you look in that engine compartment, look for the cross-over pipe for the front manifold. Oh wait, there isn't. It's a cross-under. It's a nearly flat compressed piece, wedged next to the oil pan/cradle/etc. Not much room there to create an aftermarket unit, for as limited number of cars out there as their are. Again, this thing suffers from the syndrome of size 10 engine in a size 5 dress.

As to tuning, Madtuner I'm not sure if he gets into the actual fuel and ignition curve tables. I think most of what he changes are purely settings. I.E. torque management, shift points, and other settings type of info. I had one of the programmers for HP Tuners hack into mine (they're here in Chicago), and he was able to make tweaks, but I don't think it was a full blown tune either...

Please don't put any gaudy hood on the car...

I had cobbled together a CAI I made out of spare CAI parts from other vehicles, 180* t-stat, NGK TR55 plugs, Magnaflow Exhaust that I fabbed myself, and a few other things here and there sprinkled in. At the end of the day mine sounded better, pulled better, but I never tracked it so I don't know what it ran. The straw that broke my back was nearly being beaten by a newer toyota Camera V6.

THis car is a nice, smooth, quick car, but it is not meant to be a hot rodders dream. If you want a V8 and you want to modify, you should've bought something with an LS motor. Otherwise, yes, the L67 in Bonneville's is the preferred direction.

Dammit!!!!!

Well, I'll try to do my own CAI, get exhaust work. I'll ask those guys at madtuner what i get for 350, if i don't get much like bobgto65 said, I won't buy it. And I think that would be it...

CMNTMXR57 do you know the part numbers of the pieces you used for the CAI?

No. I just raided my box of spare CAI parts. The bulk of it was a Speed Inc. CAI for a GTO. But alot of the remaining were spare Spectre aluminum bends and silicone tubes I had.

At first, I just left it in the corner (where the stock airbox was), but I kept getting lean codes, so then I sleeved it down, found another bend, and tucked it down through the hole behind the headlight and into the spare void behind the infamous sh*tty fog lights on this car.

Okay, cool.
I'm gonna try to do it probably this weekend.
Oh, did took any pictures of it? That would be great to see!

No.

Hmm... Okay cool no problem! Thanks anyways!
I'll post some pictures!

Oh by the way guys I saw this the other day and I wanted to share it with ya'll.

http://www.hotrod.com/pitstop/hrdp_1006 ... _question/

Read it and let me know what you think!

Been posted and discussed before.

At the end of the day, trying to do anything to an LD8 like that is an excercise in futility. Unless you have unlimited funds. If modifying it is your ultimate goal, get rid of it, and get an LS powered car and be done with it. The LS has an enormous, nearly endless aftermarket.

If you're insistent on staying with a "Northstar V8", GM already makes a blown version. Although it's only a "Northstar V8 in the matter of sharing the overall design and bore center lines with the Northstar you have, otherwise, it's a completely different animal. Get rid of the Bonneville and get RPO LC3 that's installed in Cadillac STS-V's and XLR-V's. And even then, after a few base mods, there isn't a large aftermarket for them either.

I agree with CMNTMXR57. I like my GXP for the looks, smooth ride and all the creature comforts, but I have a 2009 G8 GXP with a 6 speed manual and 415 flywheel hp from the factory and am getting a 2009.5 G8 GT to mod to about 400 rwhp. You can get a heck of a lot more hp from these cars than any Bonneville. Plus the planned mods on my GT will give me much better gas mileage then my Bonneville.

Bob's getting a GT?! Nice! Are you keeping the Bonne, or selling it?