Speed Inc gave me a good deal on them and will have them installed there on the 26th of this month. I'll also be running a Dynomax Bullet Race Magnum muffler in place of where the cat would be and they're obviously going to swap out the plugs & wires for new ones too. I know from first hand experience this going to make my GMMG sound a LOT meaner!

I'll then be heading over to MadZ28's place to have him tune my LT1's PCM to make sure the car is running the way it should after all of this.

I bought it last October w/ about 109,000 miles on it and the car has ran perfect up to this point (knock on wood!). So I'm hoping it will run solid mid 13's @ 103-105 come this spring on new street radials with a Moroso CAI, GMMG, Mac's/no cat, LT4 KM, & a MadZ28 tune. Trans will be rebuilt w/ a bigger stall & 3.73 gears before summer...Just not sure if the car already has 3.73's in it or not??? Last owner said he thinks it does. I guess I'll find out when Ion tune's my PCM in a couple weeks...

Can't wait to get it out to the local 1/4 track...

Mike

 

Obviously (forgot to put it in ), my main question is what kind of gaskets to you Mac owners use and have you had any problems with them leaking any?

Otherwise, I've heard nothing but good things about them for the most part (including their good plug clearance which is usually a b*tch with most other headers available).

 

Their not bad headers, with the stall, gears on tires should crack in to the 12s. Best way to check is to pop that rear cover off and check for what gears are in there. Be a good time to change the gear oil any way so might as well. Do a search on header gaskets and you'll find a good bit of info.

 

Any idea on what the damages from Speed Inc are gonna be for the install? Ive been tempted to have the headers I want to get installed there, but im under the impression that it will effectively double the headers cost. PLEASE correct me if im wrong!

 

I used Mr. Gasket Ultraseal gaskets on my MAC headers. Work great. Very similar to the Felpro's.

Running the wires in the stock location works great with MAC headers. I didn't change a thing with my wires with the MAC's. I still have stock wires, only 68k miles.

I think cracking in the 12's is optimistic. I would bet on mid 13's at 102-103 or so.

Dan

 

I used Fel-Pro gaskets with mine. Once I got all of the bolts tightened down, they sealed up great without any RTV.

 

Headers cost generaly between 275-300$ to install.

 

My Felpro's are working good on the Hookers, but I think stereomandan originally used cooper on his and they leaked like crazy, alot with a few other members who went that route. Your going to love the GMMG with headers, good luck, hope you run low 13's.

-Dustin-

 

Anybody used DeadSoft Aluminum gaskets on MAC's?

 

I just used GM stock LT1 manifold gaskets... cheap and no leaks.

If you want to know what gears are in it, drive down the road in 3rd gear (1:1) at 70mph. At that point your tach will correspond to your rear gears.... for example, if you have 2.73s, the tach will read ~2700rpm in 3rd at 70mph. The 3.23s about 3200, 3.73s about 3700... and so on. If you're in question about the speedo calibration, then just get a buddy to follow you out to the freeway in their car/truck/whatever and let them drive 70mph while you stay beside them in 3rd. Check your tach and that'll give you an indication of what gear you have.

 

I believe those are the same gaskets Speed Inc is going to use with my Mac's. They said they've had good luck with them not leaking, etc.

Well depending upon what gear I have in there now, I should definitely be able to pull off mid 13's on my fairly new street tires and probably low 13's on some Nittos. I definitely plan on having a consistent high 12 second "bolt-on only" car once the trans is rebuilt with a better stall converter. Can't wait to find out come another couple months...

Dustin...Believe me, the headers seriously WAKE up the GMMG...Right now, it's actually kinda tame to me, but if it sounds anything like Bob Steven's LT1 w/ Macs & the GMMG (which it will), I'm going to be doing a whole lot of this . His car sounds noticeably louder & deeper than mine right now. Same exact thing happened when I put the Kooks longtubes on my LS1 that already had the GMMG.

Thanks for the replies guys!