TTi shorty headers v ministarter

I just did a SL6 to 360 Magnum swap in my '67 Dart. I have planned this from the get go, I already had heavier torsion bars, sway bars, beefier leafs in the back, 8.75 posi, bigger brakes, 15 inch tires, etc. The 360 Magnum is a HUGE change in power (dyno'd at 375 hp/420 lb-ft). All good with the swap, I'm very happy with the conversion...that 360 mag is a BEAST! I'm running 2.76's in the chunk, but my A904 has lower-than-stock first and second gears. Even with those highway gears in the rear, it will easily smoke those 215 60R/15's. Sorry, I digress...on to the issue at hand.

There is one thing. On cold starts it cranks and starts quickly, but I noticed that after I've driven it for awhile, the starter turns over slowly on restart. OK, the first thing I thought of was too much advance in the timing. But no, I have it at 12 degrees base and not more than 32 degrees total. Just to be sure, I even set the base timing to 0 degrees and ran it for awhile, same issue. It starts when hot, but it has that characteristic hard crank of an engine too far advanced. So, I think my TTi shorty's may be cooking the little mini-starter. The thing is, there is PLENTY of clearance between the header/down pipe and the starter, like a few inches.

Has anyone had this issue?

Brian