underpsi68

Update

I installed the sport 5 ring inserts and went out yesterday. There was a noticeable difference at idle but incredible reduction during anything off idle. At 3500rpms it was very quiet. I closed the Corsa quick and quiet exhaust to see the difference. Basically there was none lol it was just about as quiet with the exhaust open. At WOT it was nearly silent as well. As far as hurting performance, the boat ran the same top mph as before. I would say these inserts worked very well on my application.

There might be 2 problems with the inserts: 1) it might be a little to quiet which brought up problem #2. 2) I hear a loud noise from the rear of the boat now. It is my wife yelling at me to slow down. I never heard that before hummmmm.

I am thinking about cutting off a ring or 2 to see what happens to the sound level. If i dont like it the rings could easily be welded back on. If I do I'll report back.

SB

iTrader: (1)

This boat appears to have GGB inserts: http://www.offshoreonly.com/classifi...op-o63000.html
Image #5

Boat has 4 x Merc 1075 SCI's.

Trash

I run them on a warmed over small block. No power/rpm loss. I measured a 6 dB noise level drop and as others have said they make the motor sound good.

delsol

interesting -- on that 50 nortech -- I wonder how the outside exhaust sounds compared to all the others as with the bend it can't have a very long GGB in it if any....

Wild boat!

articfriends

iTrader: (1)

I have been amazed at how little if any speed loss there is even with cheap mufflers. My 272 Baja had 5" tails with stainless marine 3's, the water dumped in 1/2 inch from the tip, it was sou loud I could guarantee you driving it alot would give you permanent hearing damage. Boat ran 99.5 gps, bolted the ggb clamp ons on, boat ran 99 and small change, virtually zero difference and this was at the 1000+ hp level. 8 years later I was cruising acrossed a lake in 80 feet of water, boat suddenly got louder, stopped and one of the clamp ons was GONE. GGB at the time was in limbo for whatever reason and I couldnt quickly get a replacement. I was going to a big boating gathering where cops nail people for noise plus money was tight at the moment so I bought a set of crappy looking Gibsons that looked restrictive as hell, necked down to 4" at outlet with 5" inlet. With my medium boost pulley at the time and 30 pitch boat would run right around 96 mph, took boat out and ran w no mufflers, saw 96 and change, bolted the super restrictive gibsons on and went back out, boat ran 96 mph fwiw. Tore Baja apart last year to return it to stock since I bought a bigger twin engine boat, put Gibsons on here for sale, no interest whatsoever in them so I still had them. Fast forward to this spring, I now have my own dyno and had a cobbled up exhaust with flex tails and 5" in/out semi mufflers. Discovered 502 I was dynoing picked up 20-25 hp with open 2 1/8 race cars headers vs the flex tails/semi mufflers (went from 530-535 to 555 +/-) bought 4-5 connectors and 4 5" semi mandrel bent 90's, was going to start adding the flex tube then the semi mufflers to see what was killing hp, was in a hurry so I just stuck the Gibsons on the end of 5" double 90's. ZERO hp drop with them over straight pipes, after final tuning we were seeing 560-565 hp and almost 590 ft lbs of tq, could NOT find a measurable HP difference with or without the mufflers, without water going thru them they are louder than on the boat BUT still knock noise down to somewhat acceptablle levels to keep peace with my neighbors, Smitty

Budman II

iTrader: (1)

I'm thinking about trying a set of the 5-inch GGB's on my 489 that runs Lightnings. I am currently using a set of the larger diameter (8-inch) Corsa's that were factory equipment on some of the 25 Outlaws and other boats. These are the design that have the fixed disc in line with the exhaust and the baffles that route the exhaust and water around to the outsides and through the muffler. I have always worried a little bit about whether these could reflect water back towards the exhaust to promote reversion. The GGB's look like a better design because there is not really anything directly inline with the exhaust flow.

The Corsa's probably take some of the edge off of the sound, but I am wondering how they compare to the GGB's. Has anyone run both? My biggest issue with the sound of my boat right now is the resonance that I get from around 1200 - 2000 RPM's. It turns into a loud, booming drone that gives you a headache in a hurry. I don't typically run much at these speeds, but sometimes when you are easing into the mouth of a cove you want to run at a little bit above an idle but not necessarily up on plane either. Would also like to quiet mine down at cruising speed to make it easier to carry on a conversation or listen to tunes. I must be getting old - a set of turn-downs is getting pretty attractive. However, I still like to watch everyone jump when it lights off! Hard to have the best of both worlds without something switchable.

Budman II

iTrader: (1)

I have the same problem! Thought I had a whine coming from the front of the engine, but it turns out that it was coming from the rear seat area.

Budman II

iTrader: (1)

Also - is there much of a sound level difference between the standard inserts and the competition inserts (intended for HP levels > 450)?

TDSracing

Was looking at the GGB called the owner about sizing. The web shows a 4.5 inch exhaust takes a 4 inch insert as the jacket narrows the inside, but this Video shows my Sterling's the jacket seems to bulge outward so I think I need the 4.5 comps. I want some of the sting taken out but the low growl still there with a loud note.

turbos230

Does anyone have some used ones? I know there were some people saying they had some used ones but that was over a year ago. What are these made of??