gulfstreamcpt

Well y'all, the headers are now on..... Got them on Friday afternoon. As shown my Mel and a some others, they do look REALLY COOL!!!!!!! You've all seen the photos and will see them on your own car soon enough, so didn't see the need to post up any photos.... Yeah, these things are T*TS!!!!!!

Now, for those of you who have the Magnaflow cat-back system, gonna give you a little heads up. I've got that system and the Hogan catted DP... To be very honest, was quite suprised on the inital start-up after getting them put on.. Couldn't tell any difference in sound from the stock headers..... Have now driven the car some this past weekend and, other than an annoying exhaust leak that will need to be found, the car doesn't sound any different than before under load either... Even at WOT... Was expecting some difference noise wise, but she sounds pretty much exactly like she always has..... Don't mean to burst any of y'all's bubbles here, but just want those with the Magnaflow to be ready for not a lot of difference in the sound...

Now I, like everyone else who's gotten them on, probably need a tune real bad!!!! Don't really feel alot of difference on the ole "butt dyno"... At least at this point.... Now granted, I haven't driven extensively yet, but my preliminary findings is that it doesn't feel much different at this point. Now don't get me wrong, there are no flat spots, lags in power, any spikes in the powerband or anything like that... She pulls nice and smooth and linear thru the whole rev range like she always has.. I just don't notice that "Holy crap, there is ton of difference here" senerio... But like some have said here, things take on a whole new characteristic once a good tune gets in there. Can't wait to get a retune and re-throw her back on the dyno to compare to my best previous numbers....

But all in all, glad they are in there!!!!!!!

AlabamaGuy

iTrader: (5)

Really? Mine sounds 100% better after headers...

williamGT

iTrader: (5)

I have the magnaflow cat back and Hogan catted downpipe, but I have the resonator deleted, maybe mine will sound different, my car sounds great without the headers now, but will find out tomorrow when there on.

neilownz

I'm going to delete the res if it's not loud enough. Just got done with work and got a gasket, new bolts.

Mels SS

iTrader: (1)

I felt it right away

neilownz

Mel it smelt for a couple miles. Must be something wearing off. I wasn't smelling it when I got back home.

They got rid of the little half throttle hesitation/shift on the butt dyno for me.

williamGT

iTrader: (5)

Well boys, I just dropped off her off at the shop, hopefully tomorrow its on.

Mgpeagle

iTrader: (6)

I assume the smell is typical when new metals are introduced to heat. My Hogan DP smelled for a bit too. Did anyone disconnect the negative battery terminal so the PCM will reset immediately? If not, then it usually takes about 3 ignition cycles for it to relearn what was done.

Gulfstream,

I bet the car feels faster in a day or two.

-Mike

higsy

Hi, not nowing how the PCM works, do you mean relearning in a good way. When I put my FWI on, it felt better at the begining, but in a few days it felt like I lost some power. Does the TCM make adjustments to the increased power to preserve the tranny etc etc. Just trying to figure this stuff out..

Mgpeagle

iTrader: (6)

Yes, I mean relearning in a good way. The TCM doesn't really adjust like the PCM does. When you increase power usually the score protection in the transmission will come on sooner because it takes less power to make things go. That's about the only thing the TCM will do. The PCM is the brains of the engine and the TCM is the brains of the transmission.

I assume with the FWI you didn't disconnect the battery cable? If not, your engine was set to the old airbox so when the FWI went on it the PCM kept the same fuel readings but was getting more air so the car would feel faster. Once the PCM learns the new mod it will eventually, as close as possible try to even things out. A tune will work wonders once you are done modding.

-Mike

oshia86

Are you guys having to perform a "break in" on the header coating? Or are you just installing them and taking off?

gulfstreamcpt

Mike;
Good point that I forgot about...^^^ Since I have my WS6, the Monte is sort of a "hangar queen" to a certain extent. Have it in a storage facility and take it out every once and a while. Will have to start to drive her a little more often here for a while and see if we can get that PCM to learn a bit. I've pobably got 4-6 starts on her since the install and not alot of driving. Hope it is the PCM IS still learning and will start to feel faster here shortly. And it could be I just need to spend more saddle time in the car to notice the difference that already is there.... But getting it retuned will be a big help I'm sure....

Anyhow, will keep y'all posted..

williamGT

iTrader: (5)

Just came back from the shop to check the car, front and rear headers are on, when I left he was installing the cross over and rear downpipe section. LOOKS GREAT

higsy

I agree with needing a tune. Just picked my GXP up and I'll give my initial impressions. My mechanic found that by dropping the engine cradle made things easier to install. He also found a busted header bolt on the back manifold which he had to heat up and drill out. I had my Hogan DP reinstalled. We cut it just ahead of the cat and welded a shorty flex pipe to it. We used the flex that came with the Hogan DP and just cut it out of the unused section.
Used the old header gaskets, but there is a whistle when you step on it, so I suspect there is a leak somewhere. My other mods include a FWI as well as a Stage 2 Ported intake ( Fasterproms) and Magnaflow Catback.
It wasn't that much louder, but maybe a bit throatier (kinda like a nicer richer sound). A little better throttle response as well as a bit more in the butt dyno but doesn't seem like huge gains. Although a bit hard to tell as the roads were wet. The battery was disconnected as well.
I did notice that the rear coolant pipe was leaning up against the crossover pipe. Did anybody else have to pry there's over at all. I assume this is a good idea.
I'll be getting a Dyno tune in a few weaks once some of the issues are cleared up and my wifes Envoy is waxed up !!! I've got an electric cutout ordered so I'm thinking of taking out the res and adding a pipe with it installed in it's place. Has anybody else done it like this??

My last mod I plan on doing are Crane RR's maybe towards summer.

DavidGXP

iTrader: (14)

Crane rockers are the.. **** adds anywhere from 6-8 degrees to the cam and increases the lift.
The only problem I have is, that I'm now done with DOD, and hate the fact that the non DOD lobes have less lift. So, now I wanna cam. Probly go this route http://www.performancetrucks.net/for...d.php?t=438267
Look at his torque curve!

williamGT

iTrader: (5)

headers are on!!! but I herar a whistle at revs and wot. everything is welded.

Mgpeagle

iTrader: (6)

William,

You didn't have your mechanic attach Air-raids to your primaries first, did you?





lol.....

-Mike

williamGT

iTrader: (5)

asking if he put the TBS to the collector? lol
does this nipple on the throttle body attach to anything? right side says LS4
DP's pic:

higsy

That's what I said in my post. all welded as well

williamGT

iTrader: (5)

I hope its normal.