Exhaust for 66 GT K-code... having some problems

[MyHotRodGT]

My dad and I have just about finished our 18yr father/son project and am down to the exhaust... We need a hi-flow exhaust to handle the 289 having been bored 60+, 14.0:1 Jack Roush Pistons, running ported and polished 351W heads topped with BlackJack 3" dumps. Our dilema lies in that weve decided we want to retain the stock exhaust exit points in the rear valance AND use the stock trumpets. Wed prefer 2 1/2 and are willing to cut the trumpets to fit. Has anyone tried this or has any clue who could produce this system for us?
Im sure judging from a few engine specs y'all can see that a good exhaust is key. We've gone all-out with the engine, and trans, and just need a great exhausto get it tonned down a few decibels. Yea, the roller cam, roller rockers, twisted crank, Roush pistons, Eddie RPM II intake, and 351W heads, sound great but the sound police have cracked down on us from running open headers and so has DMV. ANy input,questions, advice, or any other form of inspiration would be great so that we can put some miles onthis car and enjoy almost 20yrs inthe making... Thanks guy/gals!

Brandon
Firefighter/EMT
New Kent, VA

 

[NorCal66]

Well, I can tell you for sure that you can get 2 1/2" pipes out the valance, I just had mine done last week. As far as performance and sound, you should check out www.mustangexhaust.com and www.exhaustsoundclips.com On exhaustsoundclips there is a menu on the top that will give you a "flow comparison data" which "will show you which muffler is the least restrictive." How they got this info, I have no idea, so I don't know if it is accurate, but it might be worth checking out. If you do decide to go with chambered mufflers, it is best to use a H-pipe, which will produce a more meaty muscle car sound. If you use straight-through mufflers, an X-pipe is better used to achieve more of a high performance European sound. Best of luck, I love the sound of my flows, but they are very generic, so if you're looking unique, they aren't for you.

 

[MyHotRodGT]

Well it is a unique car...and a very fast one at that... And I just dont want to loose that crisp cam that it has... that sweet "plunkita plunk plunk plunkita" of that high lift cam is what i dont want to muffle. Classic Musclecar is what we're going for...and I told dad that i was going to look at H pipes over the X. Thanks for the sites, im going to check em out before I settle down and slap the greenbacks on the counter.
Im guessing you have Flowmaster 40's on yours? Im lookin at flowmaster and want a Single Chamber. Does it matter where I put them in the system (closer to the headers or farther back)?

 

[NorCal66]

Yep I have the 40s on mine. Sounds pretty similar to a clip on mustangexhuast.com ...a 68 302 I think it was. It definately has that "metallic" sound that I like so much. The guy told me when he welded everything together that a thinner pipe will wield a crisper sound while a larger will make more of a boomy, hollow sound. I'm not sure on if muffler placement has an effect on performance, hopefully someone else will chime in

 

[MyHotRodGT]

I think we'll just end up putting single chamber Flowmasters with an off-road H- pipe. The sound clips seemed to be close to what I was looking for even though none of the cars had a cam. BTW, nice GT350 look-alike. Hopefully ours will get a Shelby grill and front air dam eventually.