87 GN Sound System, Speaker Options, Wiring, Electrical Upgrade


New Member
I know this topic has been covered thoroughly in the past and I've been researching and taking notes to try and compile as much information as possible from all the different threads through the years. I'm rounding out my sound system for my 87 GN and am looking for install/wiring advice, thoughts on electrical upgrade needs and interior speaker options.
I'm going with an Alpine 7618 deck paired with an Alpine 3331 equalizer. No pre-amp juice so I'll have to use an amp to power the interior speakers. Going with 2 - Alpine Type R 8" subs on the trunk deck. Not looking to tear the car apart with extreme boom.
As far as interior speakers, I'm undecided. My GN came stock with the Concert Sound II option, so I have 2- 3.5" (10 ohm) in the dash, 2 - 5.25" (I've read also 10 ohm) in the doors and 2 - 4x10 in the rear deck (4 ohm capable). The 4x10 have been replaced and am currently running Pioneer TS-A4105 models, 4 Ohm (actually not terrible). Currently factory GN deck.
From research I know the dash and door speakers are wired in parallel with the factory Y harness. I'm assuming I'll have to rewire everything individually when upgrading to match correct impedance. I know the mounting depth for the factory 5.25 doors are approximately 2.25" until you get into the window. Mounting depth on dash speakers is unknown. Looking into 6x9 adapters for the rear deck.

Any suggestions on interior speaker models and setups?
For the 3.5 dash speakers, I'm weary of putting tweeters directly in the dash, don't want them to be too harsh. Looking for a solid option there on model and location.
Does anyone have experience in replacing the stock head unit with an early 90's Alpine deck and EQ? Any tips on wiring/installation is GREATLY appreciated.
Given the additional stress on the GN electrical system with the two amps and added output, do I need to prepare for primary electrical upgrades to keep up?
I'm not a car audio expert/installer by any means, this is my first real deep dive. I'm not looking to compete in SQ, just like my music loud, semi clear with a clean install. Really appreciate any help and guidance in advance.
Post this in the "Car Audio" heading in the "Electronics" sub-forum. Go up to Tech Arena and scroll way down to Electronics. You're in the wrong area of the forum. This section is reserved for tips on how to do something.
I recently redid the entire setup in my car using CDT audio products. They have a set of crossovers that take the amp input and split it across three drivers per channel (I believe the cross over was an MX100, or something like that). My setup in the front is 1 inch tweeters in the doors, 5.25 inch in the doors (concert sound location) and 3.5 inch in the dash. These are supported by an amp connected to a 3 way cross over with signal wires going to each of the 3 components.

In the rears I made an adapter in the rear shelf to fit a 1 inch tweeter and a 4 inch woofer, and then put a 6x9 in the section under the rear window. I only used this areas for a 6x9 because the prior owner already cut the hole. The 6x9 provides the majority of the base in the car and does a really good job. I've debated putting a sub in, but for now am pretty happy with my 12 speaker setup, with the 4 cross overs being powered by a 4x75 watt amp. I've also put sound deadening on the floor, and the exterior rear quarters, and in stalled hydophobic foam in the rear panels as well as close cell decoupling to reduce vibration and resonance.

All the sound deadening was using Resonix products, which are very nice (but expensive)