Are the TTI shorties really my only option?

Might be worth mentioning so everyone understands that the source of your problem and why you need a different header/manifold option is the issue of aftermarket Magnum heads not having enough meat around the exhaust port to seal the early freeflow manifolds. OEM heads seemed to have more than enough meat to seal, but the EQ and MP R/T heads don’t.

One option I have toyed with (since I have the MP R/T heads and 340 freeflows, too) is to swap in a passenger side Magnum large port manifold (I prefer the Jeep one) and port a driver’s side 318 manifold to match and flow better. The 318 manifold matches the head exhaust ports pretty well, just needs to be opened up to match. The only unknown (for me) is whether or not the outlet could be opened up to flow enough, or if the interior of the manifold is more restrictive than the freeflow and if it would be a choke point.

I will say that I am running adapters between my exhaust manifolds and heads, and they seem to work fine. No issues so far and it has been a couple of years. I am concerned about dropping in my .99 TBars as the current .87 bar on the passenger side seems to be almost right up against the exhaust pipe, even after I dimpled the pipe a good bit. Might find out soon, though as I am itching to get the suspension upgraded.

Worse case, I go to a Magnum manifold on the right only, and leave the left alone with the adapter plates.