I ordered some denso plugs and they came with a gap of .040. From what I understand the gap is supposed to be .044. Is this a big deal? If i install them will it effect the way the car runs? 07 es350 btw.

 

I think you should adjust the gap. A single spark plug model maybe used in a variety of engines. But those different engines may require a different gap.

 

Lexus manual says:
Denso FK20HR11 Iridium
Gap of 0.043 (1.1mm)
Also states: "Do not adjust gaps ..."

From the Denso website:

• Thread Size: 14mm
• Thread Pitch: 1.25mm
• Seat Type: Gasket
• Resistor Value: 5K Ohm
• Reach: 26.5mm (1.04")
• Hex Size: 5/8" (16mm)
• Terminal Type: Solid
• Overall Height: ISO
• Gap: .043" (1.1mm)

 

This is from Denso:
Iridium Power Gapping Tips: Before attempting to gap any DENSO Iridium Power spark plug, please review the specification chart in the front of this catalog to verify the factory-preset gap.
In most cases your Iridium Power plugs do not need to be gapped. Even with small variations in the factory set gap the ultra-efficient firing power design will compensate for those small variations.
Should you decide to re-gap your Iridium Power plug, use extreme caution as improper gapping may damage or destroy the Iridium center electrode or porcelain center.

http://densoautoparts.com/spark-plug-installation

I would leave it alone

They also provided these gaping instructions:

To increase the gap size:

• Step 1: Use needle nose pliers or spark plug gapping tool to bend the ground strap up to the desired height. DO NOT LET THE PLIERS OR GAPPING TOOL TOUCH THE IRIDIUM CENTER ELECTRODE OR PORCELAIN.
• Step 2: Re-check the gap with a calibrated gapping tool.

To decrease the gap size:

• Step 1: Use the same method as above, however bend the ground strap down to the desired height. DO NOT LET THE PLIERS OR GAPPING TOOL TOUCH THE IRIDIUM CENTER ELECTRODE OR PORCELAIN.
• Step 2: Re-check the gap with a calibrated gapping tool. WARNING: Failure to follow these directions may permanently damage the spark plug. Note: Never use a round gapping tool to check the gap or to increase or decrease the gap setting.