xp3nd4bl3

Come on, I know there's at least 1 person here who's pulled his hookers/jet-hots/slp's/whatevers and replaced them with the new stepped Edelbrock headers with merge collectors. Anybody have some before and after results? I'm more interested in et/mph than rwhp, but any info would be good.

Thoughts? Ideas? Chris ARE 385?

CHRISPY

oops I thought I posted my results already?

I LOVE the headers

When the setup was first done the exhaust shop that put on the custom Ypipe just tacked it instead of 3 bolt flanging it. Didn't realize till after it was dyno tuned. (Part throttle/injector scaling is now rich due to the exhaust leak at the Ypipe)

In 2100+ DAs I went almost 124mph (123.79) granny shifting in full street trim. (11.43 ET on a 1.78 sixty)

On the dyno the headers seem to work well. Made 400RWTQ at only 3000rpm (That is better than a lot of motors with ~50 more cubes

Final numbers were ~466RWHP/438RWTQ through single cutout in intermediate pipe

I have cats on the car now and need to retune. Probably lost ~15RWHP but I need to run them due to the police/emissions cops up here.

xp3nd4bl3

Thanks Chris. I must have missed your post awhile back, sorry about that. I don't make 400rwtq until 3500, but I also peak 500 later than you (bigger cam). I wonder if there would be bigger benefits running open header with the merge collectors as opposed to through the full exhaust. I guess I'll have to try it and find out.

CHRISPY

Open headers (with ~18 inch extensions so the O2s will work properly) will DEFINITELY benefit the car. Probably by 15-20RWHP versus full exhaust

xp3nd4bl3

Thanks Chris, I'll post results when I get them. With my Jet-Hots I gained 0rwhp thru dual cutouts in the Y over going through the 4" catback, and lost a lot of tq under 4000.

God of Thunder

so chris, did you have to send them to get coated? how much did that cost if so?

CHRISPY

You have 4 inch mufflex?

I am actually looking at picking up a 3.5 inch dynomax Ultraflow (single 3.5 in and single 3.5 out) mandrel 3.5 inch tailpipe and chromed tip so I can stop having to use the cutout at the track and make similar power compared to the cutout.

do you know if Mufflex will sell just the 3.5 inch intermediate pipe?

xp3nd4bl3

Yeah I have the 4" Mufflex but I took out the Flowmaster and replaced it with a straight Magnaflow. Picked up 10rwhp at peak and went from 114db to 107db @4800. I'm not sure if Mufflex will sell just the I-pipe, I'm trying to find a couple feet of 4" Ti piping to replace mine though. That steel is not exactly lightweight.

CHRISPY

Awesome!

How did you like the straight through magnaflow in terms of sound?

Any rasp?

CHRISPY

I just ordered a 3.5 inch center in/center out magnaflow (stainless) and am getting it installed with a single mandrel bent 3.5 inch tailpipe and chromed tip. Should work out to about 250 installed.

I might actually remove the cutout all together if power looks good.

xp3nd4bl3

That's pretty much the same Magnaflow I'm using, it doesn't sound as agressive as the Flowmaster, but I couldn't stand the 2100-2300 rasp and the mind-numbing drone on the freeway. The lighter weight Magnaflow cured both of those problems, and quited the car down making it less attractive to the local law enforcement (and more attracitve to the local unsuspecting Mustangs).

I think you'll like it.

What was your raceweight on the 124mph @ 2100' run? That would have been a 10 second pass on 1.50 60'. 10 second - naturally aspirated - six speed - street driven car.

CHRISPY

Raceweight is approx 3550 pounds. Going to weigh this weekend to verify again. (will be the third scale hehe)

If I can make similar power through the 3.5 inch muffler as the cutout I am going to remove the cutout and try hard to hit as close to tens as possible through closed exhaust in street trim. (Also upgrading gears to 4.11 next week and eventually a 27 inch tire.

Thanks for the information and props!

Toonz

iTrader: (6)

Interesting finds... I've been throwing around the idea of getting rid of my MAC's and going to LT's. Thanks for the info!

xp3nd4bl3

Hey Toonz, on my heads and cam car I swapped my Macs and a single cutout to Jet-Hots with dual cutouts and went from 117.3mph to 119.8 mph. No other changes.

dug

iTrader: (10)

Chris

Where are you getting the 3.5" Ipipe from?

CHRISPY

I am going to use a 3 to 3.5 inch adapter for now. I am not sure if Mufflex will sell just the int pipe.

Also my headers arent coated. (I might do that over the winter)

dug

iTrader: (10)

Yeah, I called mufflex awhile back and they said they wouldnt sell just the ipipe, only the complete catback. Then I asked if theyd sell the catback with a 4" ultraflo or magnaflow muffler and they said no.

You might want to try calling them again to see if theyve changed. The flowmaster muffler they use is lame. Its louder than a straight through muffler and makes less power along with being heavier. I dont get it.

CHRISPY

They could make a killing just selling the int pipe. I dont get it either...

Toonz

iTrader: (6)

Damn, that makes me want to do it even more now... Thanks though, I'm glad to hear it will actually make a difference, 2.5 mph is nothing to ignore either.

FAST LS1

iTrader: (2)

Damn, I was really hoping Mufflex sold the I-pipe seperately from their exhausts.

I too want to get their 4" I-Pipe and a 4" stainless steel Magnaflow muffler. The only difference is I want the 4" Inlet dual 3" outlet muffler. Magnaflow sells their catback in this configuration and it flows very well while still being quiet but it's a 3" inlet dual 2.5" outlet.
http://www.lmperformance.com/images/parts/mf-15684.jpg
The 4" Inlet Dual 3" Outlet muffler's at the very bottom of their page, part number 14594.
http://www.magnaflow.com/02product/ss.htm


Maybe we could get a group purchase on a Mufflex I-pipe if there was enough interest, or just get them to sell it seperate?