I've seen aftermarket tubes for the TPI, like larger diameter by i think a half in or so, sumthing like that, not real sure who makes them, thought i saw them in jegs, anyway, to the question, anyone who was bought them and installed them, do you see an improvement in performance, if so, where, like bottom end or up top around 4500 to 6 grand? just curious, was thinkin about buying a set, but would like opinions first thanks a bunch

RJ

 

The runners I have installed are from AS&M(Arizona Speed & Marine) that look stock but are large tube runners. Hope that helps.

 

On a stock 305 TPI...no improvement, but combined with a larger base, ported plenum and headers....vast improvement.

 

provided you put some work into porting them and assuming you want to keep the stock plenum, the arizona speed & marine runners (tubes as you called them) are the best you're going to get. expect to open your pocketbook for them. their semi-siamesed runners are $475.