4.10's vs. 3.55's, straight pipes vs. muffs, etc. etc. etc.!!!

[a_d_a_m]

OK, this coulda gone in the "tuning", the "storyboard" or the "exhaust" forum, so let's just throw it here and see what you guys think. I feel like a n00b posting this, but it has been on my mind.

Let's first start with the talking about the two cars in question.

I've got an June '02-built Marauder.
My friend has a June '02-built Marauder.

I have 3.55's.
My friend has 4.10's.

I have a Zack tune.
My friend has a Reinhart tune (dyno tune, I believe).

I have OE exhaust, front to back. The muffs have rusted little pinholes in them.
My friend deleted the mufflers, but left the stock system otherwise intact (4 cats).

My car has a K&N CAI.
My friend's car has a conical air filter inside a homemade airbox that seems to draw more air based on how it's designed, but it connects to the OE zip tube.

My car's computer code starts with the letter K. (too lazy to go out and look)
My friend's computer code starts with the letter B.

My car's idle is a bit shaky, as though there was an aggressive cam installed, and idles around 600, 650, no matter what.
Been this way since new - previous owners experienced it, even with the old Reinhart tune that was on it. No vacuum leaks, nobody can figure out why.
My friend's car idles at 750ish and is smooth.

I have 285/50/18 rear tires.
My friend has 255/55/18 rear tires.

Best run is 14.5x for both cars, both run in November.


Last night, we traded keys and drove each others' cars. I was in front (in his car), and he was following (in my car) as we got on the freeway. I got on it pretty hard making the turn, then floored it up the ramp, but I could not out-run him. Interstate driving, his car turns more RPM's due to the 4.10s, obviously. Around town, feels a little faster, but not exponentially.



So my question is...knowing the similarities and differences between the two cars, why is my car just as fast? Based on the mods, I would guess that his car should have beaten mine, no problem. If anyone here thinks the muffler deletion is to blame, I may have to reconsider my appointment with the exhaust shop tomorrow...................... .......

[Ktorres1]

Zack tune!

[thathotrodlincn]

Some vehicles need some bachpressure in the exhaust to rum best.

[a_d_a_m]

I heard (or read, can't remember which) that the backpressure thing turned out to be a myth...?

I'm thinking about doing the muffler delete, running the car, and if I have slowed down after doing so, I'll re-install a set of mufflers...

That's the only thing I can really figure, unless anyone else has any input on this.

[musclemerc]

+1. I think your gaining from the Z tune and the CAI.
His only gains are the DR tune and the 4:10's
The mufflers have little to do with it. He's running 4 cat's and the stock H section that's highly restrictive so the absence of mufflers only makes more noise not HP.

Zack tune!

[Black_Out]

Wouldn't 410's be a hell of a lot more beneficial than a CAI though? something still isn't right.

[musclemerc]

^^If everything he posted is accurate then it looks like the 2 combinations are equal.

[Got_1]

I heard (or read, can't remember which) that the backpressure thing turned out to be a myth...?

I'm thinking about doing the muffler delete, running the car, and if I have slowed down after doing so, I'll re-install a set of mufflers...

That's the only thing I can really figure, unless anyone else has any input on this.

its all about exhaust velocity, not back pressure.

[1 Bad Merc]

I personally would not delete the mufflers. I did that with an 88 5.0 and was racing a camaro on the tollway when I heard two very loud bangs! Then my car basically just fell down and I could not get it to move very well. It turned out that the cats had sucked throught the exhaust pipes and since their was no backpressure the motor just basically almost shut down. I was told I was very lucky that I did not suck any exhaust valves. It was very scary because I thought I had killed the motor!

Now here is the good part! Since I live in the great state of Illinois I still had to do emission testing. Well, another set of 4 cats is very expensive and it cost me a good buck to replace them and I also put some dynomax mufflers on too.

I would put some type of performance mufflers on just to insure the above does not happen to you. Just my experience and .02.

[Blk Mamba]

and mines still faster then yours "stock".

[a_d_a_m]

Hahahahaha...


Update. Took the car into the shop and they put it on the lift and said "oh, we can't do this because the inlet and outlet are two different sizes, and we can't flare pipes here."

WTF?!
But while the car was on the lift, I went under it front to back and was amazed at how clean it was. And apparently the little pinholes I thought were dripping were indeed little drainage holes. I never believed that that's what they were...

[musclemerc]

Hmmmm... drainage indeed.

What are you trying to get done? Diffrent size diameter and flanges?

[a_d_a_m]

Nope, just delete mufflers.

[prchrman]

Looks like to me you went from a roll and not a dead stop. The 4.10s would be more advantagous from a stop. I noticed this when I drove another guys MM when he had a tune and 4.10s and a CAI. From a dead stop it felt alot stronger but from a roll it did not seem that much more powerful than my bone stock MM. When hitting an on ramp he punched it from about 35mph and so did I in my ole stock MM and suprisingly enough he did not pull me hardly any at all. Might have been I hit the sweet spot for down shifting or something but I could not gain and he did not pull on me. It also has to do with individual cars and how they perform individually. I would like to see the same person drive about 10 stock MMs in the 1/4 mile and see what would be the difference. Probably more than you think.

[Phrog_gunner]

Nope, just delete mufflers.

I think you will highly regret doing this.