What if any gains would you see from gil wet at the tip exhaust going to etops?

Save your money. I spent alittle over 6k a few years ago on CMI E-Top headers for another boat that I had. I had to have custom tails made and the tails were expensive. I only went 2 mph faster with the CMI's on there. I can not relate how pissed off I was. I pulled the CMI's off and put a set of Eddie Marine manifolds with the long risers on and still went 2 mph faster than I did with the Mercruiser manifolds. Never again will I spend the money to buy CMI headers. If you want bling...spend the 3k+ for the headers, but if you want performance...get the EMI manifolds and the long tails. You will get performance from both, but you can get the EMI's for less than 2k.

That's not really what is going on here, I replaced a set of leaking Cmi's with some Gil manifolds I had, freshened the top ends and lost 5 mph and 3-400 rpm. Average leak down was 60% so I'm expecting it to gain even a little bit.

Red!!!! my buddy's talon did gain 2mph maybe!! after spending a ton on the cmi's.Took off sold the cmi's put his gils back on,put about 2 grand back in his pocket.Took some tails and modified them a little making like a stepped collector and gained 3 mph.So in my opinion and what I have seen Unless you got the big tube straight back headers on big motors were gil's cant't be used I wouldn't waste my money. My 2 cents JOHN SR

So 2 mph is the consensus. Looks to be this is part of my issue, I think I need to tune the carbs a bit more for the stronger vacuum signal they are now getting with the fresh heads. May be running a bit rich and knocking another 15-20hp out of it.

I gained Zero going from Gils to CMI's on my 525SC.

I think a naturally aspirated engine may be effected slightly more though

CMI Sport Tubles would maybe gain 2-3 MPH over Gills. E-tops will likely get you +/- O MPH unless you go dry to the tips.

On my last boat I ran Stainless Marines and then switched to Eickerts. I gained throttle response and maybe 1-2 MPH on the top end.