I've heard really good things about the performance and sound of this kit, but when I was looking through the Summit Catalog, it said that this kit comes with a single driver's side outlet, not a dual outlet. Anybody who has this exhuast system know what the scoop is? I don't want to have to buy a separate muffler just to get the look I want.

 

I have the full 3" American Thunder system on mine (not sure of p/n but I can find it if needed) and it has one 3" intermediate pipe that comes in three pieces. Two of the pieces are on their own, one to the cat and one to the muffler assembly that has the last piece welded to the muffler. That last assembly with the muffler and the third piece of the intermediate pipe is the part that goes over the axle. I think they do this to make sure the muffler sits at the right angle to get the tips on right since they are so big.

So the system has the 3" intermediate pipe, mandrel bent, and than dual 3" outlets on either side that have polished stainless ends on them that are about a foot and a half long. They are slash cut, angled towards the ground. So the entire system is three inch and it has polished stainless tips.

I called Flowmaster and got the lowdown directly from them. I saw some stuff in Summit and called them but they directed me to Flowmaster to get the right part number. The system is fairly new. I have seen a couple of fourth gens with the same muffler tailpipe setup since I got mine this spring, but I had never seen this kit before that.

My system sounds awesome but a lot of that has to do with the engine that is blowing through it (see sig). Email me if ya have any other questions.

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, K+N cone, AFPR, TB bypass, AirFoil, !AIR, !A/C, !EVAP, ARAP, 2300 stall, Hotchkis STB.

 

It's true, the Flowmaster American Thunder is a single oulet system. Without exmaning the tubing closely it fits on just like the stock exhaust, just bigger. As far as looks go I the the shiny flared 4" exhaust tips, but if you want two mufflers on there I think you stuck. Right now I'm using the American thunder in combination with edlebrock tes headers and at idle it makes a very noticible dull roar. I like the fact that the exhaust has a strong bass. Personally with my setup I think my car is pretty loud, and if it was any louder it would probably annoy the hell out of me and damage my hearing on a daily basis.

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Drew Veeneman
87' Camaro
Jasper Class II 350 (.3 over)
World Products S/R iron cast heads
Stock auto 700r4
Snail like 2.73 gears
3" round K+N Air Filter
Road Demon 625cfm
Edlebrock Performer Intake
Cheap rebuilt distributor
Edlebrock TES Headers
3" Cat+Flowmaster
Ugly olive drab camoflauge paint job
Check Out Sharky at https://www.thirdgen.org/rides/index...ew&rideid=3002

 

I don't want dual mufflers, just was wondering why they'd replace a stock dual tailpipe system (1 inlet 2 outlet muffler) with a single tailpipe system (1 inlet 1 oulet muffler). But I've heard from some other people that they've gotten a dual outlet muffler for their L98 with the AT setup and only 1 of the applications actually comes with a single outlet, so I guess I'll talk to the sales representative when I have the money to order it.

 

HELLO!!!!??? Did you read my post???? Mine has DUAL 3" OUTLETS. ONE MUFFLER. DUAL OUTLETS. JUST LIKE STOCK EXCEPT THEY GO STRAIGHT OUT THE BACK AND THEY ARE MANDREL BENT 3" WITH 3" STAINLESS TIPS.

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, K+N cone, AFPR, TB bypass, AirFoil, !AIR, !A/C, !EVAP, ARAP, 2300 stall, Hotchkis STB.

 

Matt must have a different part number than most guys. I've had mine for 2 years now, daily driver in Kansas winter and it is in pretty good shape. Mine is single in/out. They say that they make more power than the crossflow style, but who knows. The duals look better, do like matt and call Flowmaster for the right number. I think they sound great.

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'87GTA w/ SLP Cold Air, MSD Coil, Airfoil, Gutted MAF, AFPR, TES Headers, HI-FLOW CAT, Flowmaster Catback, Energy Suspension Master Bushing Kit

 

I just e-mailed Summit about it, cause I went to their online catalog and entered the supposed part number for my application in the American Thunder exhaust kit, and it came back telling me that it was the Force II exhaust kit. So their catalog says that FLO-17150 is the American Thunder for 89-92 305-350 TPI with dual cats, but the online catalog says its the Force II for the same application. I'll see what they say.

 

Ok, after looking through the Flowmaster application guide I found the source for my confusion. The Summit/Flowmaster part number of FLO-17150 is the American Thunder cat-back kit, but with a single rear outlet. The part number FLO-17228 is the American Thunder cat-back kit with dual rear outlets.

From Summit the 17228 is described simply as CAT BACK EXHAUST and is priced at $353.39. 17150 is the 89-92 305-350 TPI with dual cats and is priced at $229.95. Why it costs $123.44 more for the dual outlets I don't know, because the single and dual outlet 40 series mufflers are priced the same, and I can't see one exhause tip costing that much, but oh well I guess.

 

They do have an American Thunder exaust with dual stainless tips.I have it on mine...it will take me a few minutes but I'll see if I can find the part#...

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92RS

 

Guess you don't need th epart# afterall..lol
The cost is more because of the stainless tips.....

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92RS

 

Well, I called Summit to find out if they have a kit in stock, and they have a few. I also asked why it cost $123 more for a dual outlet, and he didn't know at all. Surmised that it was because of the muffler and the extra tip, but the 40 series dual outlet and single outlet mufflers cost the same. Oh well. He reserved a kit for me until they get my check because my lame credit union doesn' t have check cards. I hate waiting for snail mail.

 

also they reason it costs more is b/c of the tips.. they really look sweet.

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91 camaro RS
- 305 TBI
Mods: Performer TBI intake, 1" TBI spacer, K+N, jet fan switch ,160 thermo,Accel control module, Jet Stage 2 chip, edelbrock TES headers, Compleate 3" Flowmaster exhaust, Edelbrock springs, KYB struts and shocks, 700R4 built by TSI, SLP tq converter, b+m trans cooler, white guage faces, megashifter..
next month: spohn LCA's and panhard rod, BMR relocation brackets, 323 gear, lt1 cam , 350 heads

 

I have the Flowmaster American Thunder dual catback system sitting in the box in my garage. It's part number 17233 and lists '86-'91 high output, single cat and dual stainless tips. The muffler is also of nice quality. I'm having it installed shortly, so I'll let you know how it sounds. Should be awesome with my mods (I hope)!!

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'92 RS, ZZ4/LO5 10:1 350, Edelbrock 6085 heads, Crane 208/214* 467/482" 112* cam, GM/LT4 1.6 roller rockers, Edelbrock Hi-Flow TPI base, runners & 52mm TB, Accel 24#, SLP/Jet-Hot 1-5/8" headers, Catco 3" cat, Flowmaster 3" catback, Hughes 2500 stall converter, stock 700R4, 1LE driveshaft, SFC, Auburn Pro posi w/3.42, 17x9" ZR1 rims w/BFG tires, Medium Quasar Blue w/white SS stripes, Zaino...

 

This might sound like a stupid question, but..

Will the system for the 91 and earlier models fit on a 92 car without modification? I'm kind of shopping around for an exhaust for my car at the moment and I really don't want a force II system on my 92 RS :P



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1992 25th Anniversary Ed. Camaro RS

 

I'm not sure if you'd have to get the Force II for a direct fit. Depends on if you have a V6RS or a 305 and if you have a single cat or dual cats I guess. The best thing to do would be to call a Summit rep and tell them your application, then they can help you find what works.

 

Yes, older systems will fit. I've used many Flowmaster part numbers on my '86 & three '92 RS Camaros. I have a currently have a '92 which the #17233 American Thunder system is going on.

 

I got the American Thunder cat-back system with the single outlet. The reason they designed it that way, is they say the single outlet flows better than the dual. I'm not an exhaust expert, but I am a hydraulic systems specialist. And the only way I can figure out that the single flows better is that: dual pipes=more surface area that exhaust has to flow through, more surface area=more resistance to flow. That is the text book definition relating to fluids. It seems like it might hold true for gas also.

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Ron Strayhorne
91 350 V8 T.A./ MSD ignition box & wires;Flowmaster cat-back exhaust;K&N filter;Crane perf. coil; semi-polished engine;Random Technology cat sitting in the garage til I can afford the other one

 

The reason I heard the single 3" outlet flows better than the dual 2.5" outlets was due to the muffler designs. The single is a straight-through muffler, while the dual is a cross-flow muffler, in which the exhaust has to make some turns to get through the muffler, causing a restriction, hence less power.

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Greg Westphal
'87 IROC 355TPI/A4

 

I think Greg is right about the exhaust having to make a turn, but one would be hard pressed to notice the difference in power between the two. Maybe if you put it on a dyno you could find a few HP difference, but not while actually driving the car. My suggestion is to buy a cat-back based on sound and looks, the performance will be nearly identical.

 

Azarel,

It actually is not a stupid question. I have a 92 z28 convertible and the 91 dual system did NOT fit. I did the first install myself unsuccessfully (Pipes hitting the axle on large bumps), then had 2 different shops completely take it off and redo it 2 different times, to no avail. The over axle pipe kept slamming into the axle on medium to large size bumps.

I called Flowmaster and their very unhelpful tech support person told me that "they don't make systems to fit convertibles" and "there was nothing i could do to make it work". Even went so far as having an exhaust shop rebend the pipe, but he couldn't move it far enough. I was a shame, as the dual tips looked great!

oh well...I put a dynomax 2.5" on there that I am really happy with...besides, with the convertible, the american thunder was seriously loud on the highway at like 70 mph (couldn't have a conversation inside the car without screaming!).


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1992 25th Anniversary z28 Convertible

 

I have seriously been looking into the American Thunder. But is it really that loud on the highway???? I dont think I would like that.....Anyone have an opinion?????

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1991 WS6 Trans Am
Medium Green Metallic
Beechwood interior
305 TPI
TH 700-R4, Auto
T-Tops, PW, PL, PM
Keyless entry, alarm
Flowmaster Muffler
K&N Filter
Macewen white faced overlays with Xenon bulbs
Firehawk SZ50's
KYB GR-2 Struts
KYB Gas-a-Just Shocks
Pioneer DEH-630