I have a pair of 2002 Merc 6.2L 320's in my 280 SS Formula. They have 325 hrs of mostly salt use, and I always use a Guardian flush after each use. When should I change the exhaust manifolds and risers? This will be my fourth year, I feel like I'm pushing it.

I have a 1999 SBC that lived most of it's life in fresh water. (so assume zero hrs when I bought it). I had the risers off at 400 hrs and risers were getting bad so I replaced it all. Figured better safe then sorry, I vote pull a riser and look them over and if any doubt do it. I look at them like running around on beat tires...silly to try to squeeze a couple extra hours/time out of them...you gotta do it soon anyhow why gamble.

Good idea, thanks.

I agree with mneal, check them but if you flush every time they should be good for another season or two......

Pretty easy to pull the risers and check em out . I do at least every other year as a rule .