Welcome to moparts

Moparts Tech Archive


TTI 2-1/2" VS 3" exhaust system - which to use?

My TTI headers are being shipped from Brian_Wo's favorite place. I'm planning to order one of TTI's exhaust systems for my Duster.

The car will have the 383 pictured below (Hughes HEV5056BS solid cam - .575/.587 lift. 250/256 duration@.050 108LSA; M1 single plane; Holley 750HP mechanical secondary carb), a manual valve body 727 (stall speed around 3800), and a 4:10 rear. The headers are the 1-3/4" primary ones (2" wouldn't work with P/S and the Proparts semi-fenderwells required more mods than I could handle).

Will the 3" system give me noticable gains over the 2-1/2"? Is the 2-1/2" fine for my needs?

Guys out there with the 3" system - was it a tight fit or difficult to install?

Any opinions are welcome. Thanks,


My experience is with installation of a 3" system on a Challenger. Nice system, Tight fit all around but well designed expecially with their own headers. Pain is the a#$ with other style units. Could not tell you about power differences. Sounds mean though....
Sweet Pear Companies
Chad Pearson

I've got the 3" system on my Valiant and I like it a lot. Ground clearance is less than I had with the 1-7/8" duals I used to have... :-) Still great, though. Here's a link...
BTW, I have one spot that rattles, and that's because I didn't install it quite right, I'm sure. Quality of the TTI parts are great.
69 Valiant

TX - wow! Thanks for the link, great pics and easy to follow through the assembly. That's just what I was looking for. I won't have a rear in the car when I'm doing this so a front to back install shouldn't be a problem. Those pipes are big, guess I'll have to get myself a set. If I screw it up, I always have a BFH ...

I have 2 1/2" TTI's and I wanted 3" on my b-body so I cut the collector back to the 3" diameter and it fit perfectly. I am running 1 7/8" primaries w/3" all the way with an "x" pipe.

Have had several customers buy the 3" systems and had ZERO problems.

TX_BH27 - Great site you got there! Really very interesting info! thnx
I hope it's not that tight when putting the 3" system on my 72 Roadrunner, is it?? yours really looks damn tight on some spots!

TX_BH27... I agree with the guys above, VERY INFORMATIVE website. Hell you would think TTI would have something like that. They should BUY that "Installation Documentary" from you for their own website
Thanks for taking the time to do that. I'm gonna go with 3" on my E body. Scott Brown from http://www.racemufflers.com said 2-1/2" should be all I need but I wanted some 3" "cool factor" too!

IS there such a big difference between 3" and 2.5" in a little better than stock 440 system? I just see that the 3" system is damn big in this Valiant, don't know about e-body or b-body, although think it should fit even better or is the space also so small? And what primary header difference is between 1-3/4 and 2" on a e-body/b-body? A big pain to make them fit compaired to the 1-3/4?

I've got a 3" system on my Challenger, it was very hard to install. The reason is my headers are at least 20 years old and are unidentifiable, don't know who made them. But they were so nice and fit so well had then coated and reused them. As for performance gains, only someone who has dynoed both systems could tell? Personally, 2 1/2" would have been fine for my old 383, but my engine upgrade to 440 dictated the 3", glad I did it! Tips are sweet as well.

71 - I'll probably go the 3" route too for the same reason. Don't want to get "exhaust pipe envy" in the future.

king - my motor should be revver with the cam and Eheads so my guess is the 3" might help.

Mike - I don't think the 3" would benefit much in a just-over-stock 440 application. 3" would help if you were going to be revving a motor pretty high, but a mild street motor probably qouldn't see a difference. I would guess 2-1/2" would be fine for you.

Direct_, on the subject of TTI headers. I was looking at their site the other day. On restrictions for the 2" A-body, it ONLY said 440 no power. I think in the past it said any BB. You can see, in the other models, they are very specific, in restrictions. Curious, I called, got tech girl and she said no, when I mentioned agin 383/400 not 440, she seemed confused. Said she would ask "Sam" the designer. He told her that 383 or 400 would fit with PWR STRG..!!! Any other input on this. This was maybe Fri., seems they have revised their restrictions.


Back to Tech Index
Tech Index