Which dia. full exhaust, 2-1/2" or 3"
406 ci
292h cam
#16 heads,ported,filled,ss valves
comp. 9.7
headers 1-3/4, 3"collector
modified rpm intake/Qjet carb
curved hei/msd 6al
4spd/3:55 gear
Will the 3" kill low end torque?

Which dia. full exhaust, 2-1/2" or 3"
406 ci
292h cam
#16 heads,ported,filled,ss valves
comp. 9.7
headers 1-3/4, 3"collector
modified rpm intake/Qjet carb
curved hei/msd 6al
4spd/3:55 gear
Will the 3" kill low end torque?

Good question--I was thinking of ordering the 3 INCH system for my 77 SE T/A --455 .030-- HORACING RAM AIR IV grind cam-headers etc. will be adding a BM HOLESHOT conv. is this a good converter with a 3.23 gear.

2 1/2 is plenty big enough. With that cam I'll wager you need all the low end you can gather. http://forums.performanceyears.com/g...icon_smile.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by David Jones:
2 1/2 is plenty big enough. With that cam I'll wager you need all the low end you can gather. http://forums.performanceyears.com/g...icon_smile.gif <HR></BLOCKQUOTE>

I was thinking with the specs below I should go with a 3". The one thing that will probably change will be a set of KRE heads.

I may be wrong but i thing that header size is more important than exhaust size. Besides with a normal bent exhaust system 3 inch usually bends down to 2 1/2 in the turns. Even with 3 inch manrel bent systems i have never seen a loss in 400 ci and up motors especially with ported heads. Beside if you ever want to upgrade the motor in the future you don't have to buy another exhaust system.

"Cut-outs" or "dumps" work great on a street/strip car IMHO. There are quality electric ones available now. You could wire them with a WOT switch for hands free operation and stealth at the lights.

I use the Jim/Tom Hand deign....
from the header collector; 3" with X-over, to 3"x2.5" Flowmaster reducers in front of 2.5" inlet/outlet mufflers, to 2.5" tailpipes.
'79 T/A

I have a pretty much identical setup except i'm using the normal Performer, not RPM.

I opted for the 2.5" system with X to retain some low end, but with a 5speed box, there is plenty of gear there so getting it to rev isn't hard either.

Unless you're in the 500+HP range, I wouldn't bother with 3". Tighter clearances getting the pipes over the diff etc..

I use 3" pipes off the collectors, 3" H pipe into two chamber Flowmasters that are blown out to 3" on the inlet side. They exit into 2.5" full length tailpipes. Non of the pipes are mandrel bent so one would think it would be somewhat restrictive. Even so I've ran [email protected] with this set-up......Cliff

Thanks for info!
I have a 2-1/2 custom made set-up, all flanged to ease takin in and out. The X crossover was made straight so when you look thru it at any end it's looks perfectly thru 2-1/2"s. I was going to fit it to my Z71 getting rid of the cats...maybe later? I read somewhere(Carcraft) if you take a vacuum gage to the exhaust to see if big enough? If it makes a sertain number of "s of vacuum or more the pipe should be bigger, I'll look for it again. By the responces and the exhaust pro that built it I sould be able to throw quit alot of HP to it.
Thanks.

My opinion(for what it's worth?) I would go with the three inch. Your collector is three inch(even flow). Your muffler will make up for the back pressure you need(depending) with your set-up. Going to the three inch exhaust, you will then be also ready for upgrade of engine flow in future. Unless of course you plan on staying in the perimeters of where your at?

Is that cam the 292AH-10?

My friend has it in his 70 GTO and it rocks!

I'd say go with the 3"

What mods did you do to the RPM intake?