spark plug choices

I'm changing the plugs and wires in my '00 gtp. I'll probably be buying the Taylor 8mm spiro pro wires. Is there any reccommended spark plugs I should consider?

And another question I had was, are MSD ignition coils worth the extra money?

Is your GTP stock or modded?

If its stock AC Delco either Platinum or Iridium. If modded the Autolite copper core is what most of us use. NGKs are a good third choice. No Bosch.

Taylor Spiro Pro 8mm wires are a good choice and work. MSD Blaster coils are nice but probably no better than the stock coils. Better color choice. They do look nice. I've got the MSD Blaster coils with MSD 8.5mm wires and there is no way I can prove they are any better than stock.

Bosch plugs: When you like piece of metal in your block....



Personally I run Autolite 104s(just recently changed the wires and plugs)...

as far as wires, i recommend the stock AC DELCO wires, from what I hear they are as good as any wire you will buy and are cheaper than Taylors...

Strongly suggest going back with OEM plugs. I change mine to the autolites and 3 days later it started affecting my ignition and the engine started missing vilently. Took it to the pontiac shop they knew right away i had change my plugs and said that i was luck i did not damage the coilpack. $157.00 later it ran fine. PS..... not that having to deal with the angle of those plugs and the O2 sensor is worth every cent.

that is just freak, MOST GP owners will agree, if you're running more boost than stock, 104s and 103s are the way to go...

Thorn, what your dealer told you was crap. A bad plug wouldn't damage a coilpack. You probably had a loose plug wire or a cracked plug porcelain (which may have happened during the installation), and the stealership took you for new plugs at their rediculous price. I would have asked for the old plugs back to see what they were referring to. The only difference between Platinum and regular tipped plugs is longevity. Platinum/Iridium is denser than iron, so they won't erode (wear out) as fast. Modders use the Autolites because their less expensive (longevity isn't an issue because they change them/inspect them regularly) and it's easier to determine heat range differences with Autolites numbering system.

that is just freak, MOST GP owners will agree, if you're running more boost than stock, 104s and 103s are the way to go... i dont think boost was the subject.

Much Respect: RICHTAZZ i can believe that their familys need to eat to. I value this dealer ship of course its just not as painful when surprised vs expected. This vilent missing can not quite be apprecitated third person. meaty content goodjob guys

that is just freak, MOST GP owners will agree, if you're running more boost than stock, 104s and 103s are the way to go...

I agree but with the stipulation of GTP owners.

i dont think boost was the subject.

Boost may not be the subject if your GTP is stock when it comes to spark plugs but it is always relevant in discussions involved modded GTPs where a smaller SC pulley is used to increase boost. I inferred that is what 04GTP-WhatLAG was talking about.

If you are running the stock pulley (3.8") with stock boost then stick with the OEM AC Delco Platinums (41-921) or AC Delco Iridiums (41-101). Using Autolites (copper core) when stock serves no purpose. However, the Autolite Platinums AP606/AP605 work fine and will last as long as the AC Delcos.

As pointed out if modded with a smaller SC pulley 3.4" and less, most of use Autolites. Reason is the easy numbering system and cost due to more frequent replacement. Higher boost = knock retard (KR) which will possibly damage the engine (detonation) and causes the PCM to modify spark advance and timing ruining performance. One method of controlling KR is to use colder spark plugs.

The problem with using AC Delcos when modded is the lack of availability of suitable colder spark plugs and the numbering system leaves alot to be desired so even trying to figure out what AC Delco has for colder spark plugs is very confusing.

See here for Autolite Copper Core spark plug heat ranges


Autolite 606 = stock heat range
605 = one range colder
104 = two ranges colder
103 = three ranges colder

I just replaced the plugs and wires in my 2002 Grand prix with autolite dubble platum plugs and seen no difference in perforamce or mileage should of keep the old ac plugs and saved some $$