I saw a very noticeable gain going from 1 5/8" to 1 3/4" when i had my ysi...big like 22 rwhp...and that was the only change I made at that time...

 

Did you have 1 5/8 long tubes before the 1 3/4 longtubes?Or were they shotie headers.

 

yeah they both were long tubes 1 5/8 pace setters and went to 1 3/4 hooker long tubes...i was using a comp cams hydrollic roller blower cam...

Lift numbers with 1.5 ratio rockers
Duration 224/229
Lift .528/.510
114 lobe sep.
110 intake centerline


i still have the cam if you know anyone that wants it...only has about 1000 miles on it...was perfect for my street car...

 

I don't agree... nor any of the engine simulation programs either....

I gained over 50rwhp going from 1 5/8 to 1 3/4, albeit it was from shorties to LTs.