Spark Plugs and Possible Exhaust Leak

[mrcid]

Can someone help me out here? Thanks in advance for all replies.

Here's the issue: My '07 with V & H setup, and Fi2000 has had the decel cackle since I had the dealer change the pipes last year. I've always thought that the settings of the Cobra unit (3, 5, 0) was the issue, and I just couldn't get it just right, so I messed around with it for a while, and just left it alone. Now is bugging me again, and I want it stopped.

Now, after reading a bunch of related info on the site, I believe I may have the dreaded exhaust leak, but tried to find it yesterday and couldn't. I ran smoke around every joint and connection in the pipes, and didn't notice anything peculiar. Called Cobra, and they advised me to plug up the exhaust in an attempt to see if the bike would stop running once plugged up. Used a towel in both ends, and nothing happened, bike kept running. Does this mean there is definitely a leak? And what else can I do to find it?

2nd issue: I just finished reading the threads and posts regarding spark plugs, and just so happened to have changed mine yesterday. Went to the dealer who looked up the stock plugs (DPR6EA-9), had them on the counter, but then noted a conflict in websites citing two different plugs. Tells me his parts fiche cited the DPR5EA-9 for the '07 Nomad, and sells me those instead.

Now, I am NOT a mechanic, and know nothing about engines, and took his word that the "5" plugs would work fine. Reading about the temperature differences in the engine now has me slightly concerned.

Should I worry about the "5" plugs causing any damage, or will all be good?

Again, thanks for any help you can provide, and my apologies for the long post.