I need to see what an LT1 intakes flow #'s are. I want to know when they start to choke an engine as it gets up into the higher RPM ranges. TPI intakes choke a motor after about 4k RPM anyone know off the top what an LT1 intake is good for?

 

In raw form, they'll run a 350 up to about 5,500 with no flow impediment. If the ports are raised, enlarged, and the heads are given a similar treatment, the intake will flow enough to run a 350 up to about 6,300 RPM before becoming a serious restriction.

Of course, that all depends heavily on the VE of the engine, which is controlled to a large extent by the valve timing and cam profile, and to some extent by the head runner and chamber designs. Improved heads and valve events that increase the volumetric efficiency of the engine may cause the restriction to be more apparent at lower RPM. For a relatively stock valve train and raw heads, however, those numbers follow the peak power curves of a generic LT1 and LT4 engine, so should be a reasonable guide.