Hey guys, Im thinking about putting some MAC midlengths on my 00 Z28...The package will include the headers, highflow cats in the Ypipe and a 3 1/2in electric cutout after the Ypipe. I have SLP loudmouth on it already and just want to hear some of yalls opinions on it. How it sounds, performance issues, reliability and durability, *any other suggested headers or set ups*, overall too. Im planning on putting a SLP Cold Air package to help out the breathing in the near future. Thanks for everyones help.

-Philip

 

For the price of new midlengths and a Y w/restrictive mac cats, you can get longtubes (Pacesetter or Flowtech) and a offroad Y and get some highflow cats put in them. Either way, your loudmouth will be quite loud.

BTW, don't waste the cash on the SLP cold pack. Get a lid (a used one or quatermileperformance.com has new ones for $75) and then get a SSRA (Super sucker ramair). You should still have some change left over and have more gains. There was a special on ls1tech.com for the SSRA.

 

putting the cutout on the loudmouth is pointless, it is basically a muffler-less exhaust...what's the point of bypassing that?? you'll see little to no gains from the cutout.

anohter thought is that the Ypipe for the MACs will be 3"..how do you plan to put a 3.5" cutout on it?

and forget teh SLP cai....it's hardly worth it. if you want a real gain go for something like the SSRA. which has a scoop under the nose of the car for a ram air affect at speed, and at slower speeds it acts just like the slp cai. i have a link in my sig

 

Thanks for yalls replies...I was told at my local performance shop that getting Pacesetters and putting highflow cats on a hooker Y pipe (they say the Ypipe that comes with the pacesetter sucks and has clearance issues) that it would be too low for my car. I want cats on the car to be smog legal at least for now. I also want to put cutouts somewhere on my car I first wanted to put it before the cats, but the mechanic said that the engine needs back pressure so I dont lose all my low end...They recommended putting it after the Y pipe. If you have a better place for them to be put please reply with some recommendations. Thanks all of yall for your help

as for the cold air...thanks ill look into yalls suggestions and really appreciate all the help.

 

i think the mids are a good choice....compromise between function and clearance.

don't know how the MAC cats are though.

but i still don't see a need for a cutout on a loudmouth...basically putting a cutout on a straight pipe....

putting the cutout before the cats will probably hurt your low end a little, but the upper rpms should benefit. that's a tough call. although you won't be able to run on the street much with them up there, it will be REDICULOUSLY loud and the interior resonance will be unbarable.

 

"but the mechanic said that the engine needs back pressure so I dont lose all my low end..."

Find a better mechanic. Its exhaust velocity not back pressure that will generate more torque. If back pressure is so great, then why do dragsters run open headers at the track?


You have to watch clearance with the MAC Y also. I had to remove my tunnel brace for it to fit and it is VERY close to the driveshaft also. I have MAC's. I picked them up used w/a MAC ORY w/carsound cats installed. Had they not been a decent deal, I'd have gone LTs.

 

thanks for the replies, but I thought that LongTube headers give more torque and HP because they are longer and have no openings. Isnt that why Longer is better because it creates more back pressure then shorties dumping right into the Y pipe.

 

Nope. Keeping each cylinders exhaust in a seperate pipe for the right amount of time causes better scavanging, which is where you get the power.

 

Thanks for the replies...So putting cutouts before the Cats on a y pipe wouldnt kill my torque considerably? My main goal is to get a deep throaty sound like the GMMG creates...I was thinking that putting the cutouts before the cats would give me that sound and not a loud rasp that the LM creates...and if I want it to be quieter I can just close the cutouts.

 

Have you ever looked under your car? There is no room for cutouts before the cats.

 

ive been doing some research on the macs as of late and there y-pipe sucks *** and there cats flow like crap.

i think your best bet is to get pacesetter long tubes with tsp's new catted y-pipe.

 

The GMMG has its sound because it has 2 mufflers. You could try putting a chambered stick (or spiral or bullet muffler) in place of your resonator. Be careful if you do go with the chambered stick. Some of them decrease the tubing diameter by .25" inside the muffler.