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Since my heads and cam upgrade on my 05 turned into a full blown overhaul (with the exciting news that the block was already .020 over) my funding has been mostly burned through. I’ve got JBA longtubes and mids but still have the factory cat-back. My question is, would I be better off getting the Dorman LS2 intake and an SLP loudmouth cat-back or just getting a Fast 102 and leaving the stock cat-back on? Chances are if I do just the Fast it will be quite a while before I will be able to do a cat-back.
 

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Depends on your goals. Do you want to make more power or sound louder?

If memory serves, there's not much power to be made in doing a catback on these cars - the real restriction is in the catted mid-pipes and you've already replaced those.

I'd say with the mods you have, go Fast 102 and be happy with the sound until the money rolls back in.
 

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Discussion Starter #4
I’m more worried about restriction in the cat-back than sound, if stock isn’t bad I will keep it and do the Fast. Thanks guys
 

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The FAST will probably gain more than going to a better catback system.

You should stand to gain going with a nice flowing catback though, just not nearly as much.
 

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if you want your car to sound like SHIT, then yea, get the loudmouth. The most horrible exhaust ever. Hell I just cut one to pieces saturday and tossed that junk in the dumpster. I wouldnt spend the money on the fast either. Get the dorman ls2 from rpm speed and have it ported from them. The fast is way over priced in my opinion.
 

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go with the MSD over the fast, it will have even better gains. A 3" exhaust will perform better on your setup anyhow than the 2.5 so I'd just hold off on that part of it.
 

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I’d do exhaust if you have an 04. I don’t mind the slp. Sounds like the same stuff every other car have.
But I’d do the fast manifold. Decent gains and doesn’t look like shit.
 

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SLP loudmouth sounds like raspy crackly trash.

Loudmouth ii is quieter and a lot less raspy, but nothing to write home about. The mufflers also have ridges that restrict down to a 2" diameter.

Spintechs and flowmasters sound nice, but they are chambered and chambered is never as good for flow as a straight through design.











































Smurf it, want it to sound nice and scare the neighborhood, get a cam with 16 degrees of overlap and dumps.
 

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go with the MSD over the fast, it will have even better gains.
I'm not sure I believe that at all. Do you have any source for head to head test data?
 

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Here's a comparison from the Corvette forum: Fast 102 vs MSD airforce comparison. - CorvetteForum - Chevrolet Corvette Forum Discussion

The MSD gives up power at low RPM ranges and into the midrange. The MSD has a slight advantage at and above what most of us use as a redline (I'd say about 6500). But even if the MSD is even better above 7k, who spends much time above 7k? The OP appears to have a street car and I doubt he's even exceeding the factory redline. I know I rarely do and I'm sure I'd think I'm pretty typical of street applications. On the street, I'll take the low end advantage any day.
 

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Yeah, my car is never going to see 7k. Based on the couple comparisons I saw the Fast makes more power in the rpm ranges I would use.
 

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Only sees 7k long enough to shift. Pointless to get that intake for that when there are better options for top end builds. I’d daily mine to 7k again once I get a bigger blower.
 

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Also, the comparison I shared above was on a 7.0L engine so the results on our typical LS1 and LS2 may be skewed a bit more. I'd think the larger plenum on the MSD would make smaller engines even more lazy down low.
 

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My motor sees 7k and lives in the 5700-7000 range due to my stall. she likes it. HCI setup.
That's great, just that doesn't really apply in the OP's case.

I'd like to see a comparison of the MSD and one of the race FAST 102s, probably closes the gap or betters the MSD at the top RPMs. But I honestly have never heard from anyone who has one of the FAST race intakes. To be more correct I should say a FAST with the high HP or race runners in it.
 

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ported MSD vs ported FAST 102, with an "LSSR" cam and mamo 220 heads. (to quote the thread, 237/245-112.5+2 – 232/240 hydraulic equivalent, so sounds like he went solid lifter.). so, you figure 16 degrees of overlap, "11" if you use the "hydraulic equivalent" numbers.

Fast 102 is the pastel blue and green, while MSD is the dark blue and green. The fast made more torque under the curve until 6500 than the MSD. however, the MSD prevailed over that RPM.

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personally, i'd have to have a cam that angrily spat and choked at anything under 4000 rpm to warrant switching.
 
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