I'm totally clueless on what is causing this knocking sound.

Here a little info about my Car

2005 G35. Rev-Up Motor
Greddy 18G twins installed Sept 2009
Import Parts Pro Stage 1 block installed Sept 2009
Stock Head with about 20K miles on them
HKS FCON VPro tuned but Forged

The car had 55K miles when the twins and block was installed. I'm about to hit 60K miles, and within 5K miles I did 3 oil changes. The first change within 30 miles, the 2nd oil change after 1k miles, the 3rd change 2K miles from the last change. Since I'm breaking in the motor I using 10W-40 Castrol GTX. I'm about to switch to AMSoil next month.

Ever since I leave Forged, the car has been solid. The only problem I had so far is a little exhaust leak coming from a loose bolt on the exhaust manifold. Well tonight I started up my car, and let it run for about 4 minutes to warm up the engine. As I was leaving my neighborhood I noticed a loud Knocking coming from the engine bay as I started to Rev pass 3K RPM's. I pulled over to a parking lot down the road and poped my hood to see if anything was loose, nothing. I asked my friend to Rev, and again I could hear a loud knocking coming from the engine. So I drove back home and let the car sit for 30 min and checked the oil. The oil level is fine, just below the "H".

The last 2 times I drove the car is was fine. Friday I drove from work to home (about a 30 min drive), and yesterday, a quick run to the store.

After factor is the cold weather, Its been about 32 or colder all day.


Any thoughts?

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