Found this on all data i know ive seen some posts about this concern on these forums thought id post the TSB i found
EXHAUST TICKING NOISE
'05 - '06 Tacoma
April 7, 2006
Some customers may experience a ticking or tapping-type noise from the engine area at 2000 - 2500 rpm during acceleration that is most noticeable after a cold soak. New exhaust manifolds have been developed to minimize this condition.
^ 2005 - 2006 model year Tacoma vehicles produced BEFORE the Production Change Effective VIN shown below.
Production Change Information
Replace both LH and RH exhaust manifolds.
Refer to the Technical Information System (TIS), 2005 or 2006 model year Tacoma Repair Manual: 1GR-FE Engine Mechanical: Partial Engine Assy: Replacement.
The Remove & Reinstall (R & R) of the Exhaust Manifold (P/N 17140-0P010 and 17150-0P010) due to the attached Catalytic Converter, is covered under the Toyota Federal Emissions Warranty. This warranty is in effect for 96 months or 80,000 miles, whichever occurs first, from the vehicle's in-service date.
* Warranty application is limited to correction of a problem based upon a customer's specific complaint.