After posting here, and asking your advice for what mods to start with on my LS1, I took your advice and went to work. I ordered a whisper lid and K&N filter, to help out the air intake. While installing these, I busted out the dremmel tool and went to work, I did the free ram-air mod, as well as ported my MAF. After taking the car out for a test-drive I was extremely impressed witht he HP gain for such little $$. I would estimate a gain of somewhere around 25++hp. I think the next step is to order a cat-back exhaust system..... any recomendations????

 

I was very happy with the Mufflex 3.5 I had for my Z, infact if my SS hadn't come with the SLP dual dual thats what I would have gotten for it. Good luck with your choice.

 

Cat-back!?! NO!
A muffler will do the same job. With a cat-back you are just paying for fancy tips and a sound. The stock system is 2.75" mandrel bent stainless and flows fine, the problem is the stock muffler.
If real bang for the buck is what you seek, do the Dynomouth mod!
I have a whopping $140 in my Dynomouth, and that INCLUDES professional installation. The icing on the cake is the unique muscle car sound it provides that is so hard to get from the LS1.
I dynoed about 38 hp over stock with just a Dynomouth, lid (Fram), and a few free mods that don't show on the dyno...
FRA
TB bypass
Free thermostat mod
Auto fan switch mod
Glad to see you have the mod bug!
Keep it up.
Dave

Btw: Dynomouth sound clip in sig...

 

A 3in cat-back will flow better than 2.75in (didn't know it was that big). So what when people ask what mods you got you tell them a muffler?? I know you plug this dynomouth alot and yes it sounds awsome...but everyone knows that a cat-back is one of the first mods you should do, and its that way for a reason. I have a 3in cat-back and din;t like the sound so I went with a less restrictive magnaflow muffler...but the point is that I have 3in piping, you don't Good luck on your decision, but I wouldn't just go with a muffler.

 

CORSA!!!!!!! Its a great system, flows really good, looks excellent, and sounds mean as hell at WOT, but doesn't drone at cruise. A bit pricey, but if you've got the money its well worth it IMO.

 

Most of the gain is from the muffler. 1 - 3h.p. is from the bigger .25" pipe. Not worth the extra money to get a full catback.

 

If you honestly believe that .25" larger pipe is going to help a car that doesn't have at least heads and cam, then you keep on dreaming. I have both equaled and out dynoed cars with very expensive systems. Assuming the same mods of course.
You also must know where your system stands flow wise, for example:
Borla flows around 950 cfm
Magnaflow around 1100 cfm
Flowmaster around 350 cfm
DynoMax, the basis for Dynomouth, over 2200 cfm...
All this tells me the pipes don't matter much until you get into serious mods, not the bolt on kind. Once you do something like heads and cam, you won't want to jump up just .25" in pipe size anyway... you'll be looking for a Mufflex 4" or Duals now won't you.
3" cat-backs are just a well marketed waste of money. Like you said, you didn't even know we had 2.75" I-pipes... uniformed consumers get burned.
Dave

 

I want something that sounds loud, but not obnoxous... and I want the max HP... if the dynomax deal will give me that I will do that, but to me it doesn't seem like it gives you that much hp... one thing I do know is that the flow has to match the engine... too much flow is not good and too little is not good... help!

 

I have the Dynomax race-welded muffler and cat-back and I LOVE it.It's one of the highest flowing mufflers with I think like 905 cfm.Don't listen to these guys saying you have to pay a lot.My set-up was only $150.I just bought the I-pipe and muffler,I re-used my same tips.The tips and tailpipes would have pushed the price to around $225.You can order each individual piece seperate.The sound isn't much louder than stock,but it's definately deeper and more aggressive.Good luck.
Kevin

 

I think I am either going to go for the SLP loudmouth, or the Dynomax setup... with the dynomax, I can't install it myself, correct? also, the dynomax would not pass emissions would it? anyone have feedback on the SLP?

 

http://www.exhaustsoundclips.com/cfm.pdf


What I would want to know is why the 30 series flowmaster is not on that list?!?! Its billed as their High performance while the 40, 50 and 80 series are just termed "performance".

Really makes me wonder...

 

am i the only guy on here that had a big **** flattened section in the factory i-pipe where it goes over the panhard bar? that would deffinately impede exhaust flow, and im pretty sure the aftermarket catbacks dont have that, at least my old flowmaster didnt... shoot, my 4" mufflex doesnt have it.
jeremy

 

I had an SLP LM installed on my wifes 2002 SLP SS on Sat. That sh*t is wicked! But keep in mind, you have to to bee a certain type person to want an exhuast like this! It isn't for everyone!

 

Borla with an electronic cut out!!! Quiet when you need LOUD when you want it, all at the push of a button.

 

For what its worth, going from 2.75" pipe to 3" pipe may not seem like a lot (.25" diameter). But, its cross sectional area is increased by 1.13".

Oh yeah, and I got my Loudmouth setup off of the For Sale boards at LS1.com for $150. Might want to check those out, there are good deals to be had.