Update or upgrade
Instructor
Joined: May 2014
Posts: 150
Likes: 16
From: Alberta
Hard for us to answer that for you as there are so many variables. What is the C5 that you currently own? Do you feel that your current car is insufficient in areas out side of performance? Do you have a preference for one interior/exterior styling vs. the other? What about the drive experience? Is it just a performance upgrade you are looking for or, are your looking for the LS9 specifically? Do you prefer N/A over forced induction?
Melting Slicks
Joined: Mar 2023
Posts: 2,934
Likes: 1,690
From: North Coast
Comes down to a number of things.
How good is the C5 you have and do you like the car better than a C6?
Do you live in a state that’s not going to step up emissions regulations?
There are more factors but the C5 can be more easily modified than a 6 as tbe 6 you get into more electronics.
Depending on the year what year is each car as sone years are better than others.
I personally like my C5 better than a 6 styling wise and see of working on wise.
I also have the ability to buy parts cheap so modifications may be in my future sone where.
the only C6 I really would upgrade to is a C6 Grand Sport and if I do it would remain stock. Just never got used to the headlamps and the interior feels like my 08 Malibu. Not bad but not Corvette like.
Nothing wrong with either plan both are win win. You just need to find what fits you best.
How good is the C5 you have and do you like the car better than a C6?
Do you live in a state that’s not going to step up emissions regulations?
There are more factors but the C5 can be more easily modified than a 6 as tbe 6 you get into more electronics.
Depending on the year what year is each car as sone years are better than others.
I personally like my C5 better than a 6 styling wise and see of working on wise.
I also have the ability to buy parts cheap so modifications may be in my future sone where.
the only C6 I really would upgrade to is a C6 Grand Sport and if I do it would remain stock. Just never got used to the headlamps and the interior feels like my 08 Malibu. Not bad but not Corvette like.
Nothing wrong with either plan both are win win. You just need to find what fits you best.
Moderator
Joined: Apr 2002
Posts: 11,773
Likes: 1,374
From: US
The c6 is pretty much in every objective aspect superior to the c5. In some areas more than others, but especially the z06.
You can mod a c5 to get superior power -- I'm at 530hp to the wheels and it's completely streetable -- but getting the level of handling and precision that the c6 has over the c5 is difficult.
I went through the same dilemma as you -- at the time, it was either get a new c7 or update the c5. I decided to stick with the c5, but only after ripping out the entire interior, replacing everything with black/red leather, new wheel/tires, repaint, super charger/cam etc etc. It's an entirely new car....but for the money I spent, I would be a significant way towards a c7 z06. and even now every now and then I still look at the c7 ...
Oh, and what others have said about value is absolutely true. you may be able to get a slight premium for well thought-out upgrades if you ever decide to sell, but most of the time people just don't want to pay more for other people's custom jobs. You have to be comfortable with the notion that you will be spending a sizeable amount of money and never have a chance of getting it back. It's an investment in what you want, not in any way financial.
You can mod a c5 to get superior power -- I'm at 530hp to the wheels and it's completely streetable -- but getting the level of handling and precision that the c6 has over the c5 is difficult.
I went through the same dilemma as you -- at the time, it was either get a new c7 or update the c5. I decided to stick with the c5, but only after ripping out the entire interior, replacing everything with black/red leather, new wheel/tires, repaint, super charger/cam etc etc. It's an entirely new car....but for the money I spent, I would be a significant way towards a c7 z06. and even now every now and then I still look at the c7 ...
Oh, and what others have said about value is absolutely true. you may be able to get a slight premium for well thought-out upgrades if you ever decide to sell, but most of the time people just don't want to pay more for other people's custom jobs. You have to be comfortable with the notion that you will be spending a sizeable amount of money and never have a chance of getting it back. It's an investment in what you want, not in any way financial.
Race Director
Joined: Jul 2008
Posts: 17,767
Likes: 3,694
From: The Sunshine State
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Between those two choices, I would go C6Z. I'm planning some further performance mods to my 2004 C5, however that's because as the original owner, I plan to keep it as long as I'm above ground as I chose to skip the C6 generation and added a C7Z. I had a C3 before my C5 so I guess I just like the odd number generations. 
I know going in that my mods don't improve the resale value but I'm making the changes to increase my enjoyment of the car. I prefer the looks of the C5 over the C6 so that's another factor.
If you don't plan to keep your C5 for the long haul, I would definitely go with the C6Z over spending the $$$ to get your C5 near C6Z performance.
I know going in that my mods don't improve the resale value but I'm making the changes to increase my enjoyment of the car. I prefer the looks of the C5 over the C6 so that's another factor.If you don't plan to keep your C5 for the long haul, I would definitely go with the C6Z over spending the $$$ to get your C5 near C6Z performance.
Burning Brakes
Joined: Feb 2022
Posts: 895
Likes: 986
From: NW Burbs of Chi-Town
2025 C5 of the Year Finalist - Modified
If you are doing the work yourself... Mod the C5. If your paying some one to do the mods, buy something else. IMO
I had over $7k into my head/cam/header swap, just in parts. That being said I kinda went over and above on some parts. I love it, but it was a lot of work. I've had fellow Corvette brothers ask me if I'd do the same for their C5, so I guess I did it right. I just currently do not have the time to work on other peoples Corvettes.
This is a good source depicting the amount of work involved in a head/cam swap on a C5:
http://www.ls1howto.com/index.php?article=1
The State of ILL, County Crook just plugs into the OBD port, so if there is no codes, off you go. There is no visual compliance. Don't paint yourself into a corner from an emissions standpoint, if you go the mod route.
I had over $7k into my head/cam/header swap, just in parts. That being said I kinda went over and above on some parts. I love it, but it was a lot of work. I've had fellow Corvette brothers ask me if I'd do the same for their C5, so I guess I did it right. I just currently do not have the time to work on other peoples Corvettes.
This is a good source depicting the amount of work involved in a head/cam swap on a C5:
http://www.ls1howto.com/index.php?article=1
The State of ILL, County Crook just plugs into the OBD port, so if there is no codes, off you go. There is no visual compliance. Don't paint yourself into a corner from an emissions standpoint, if you go the mod route.
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From: In a parallel universe. Currently own 2014 Stingray Coupe.
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If it were me, and I really like the C5, my choice would be to do the upgrade to the C6Z. It is a beast.
Drifting
Joined: Dec 2001
Posts: 1,808
Likes: 19
From: Little Rock, AR
Ive gone from a C5 FRC to a C6Z to a C7Z to a C5Z. My heads and cam C6Z felt the fastest. Lots of low end torque with the 7.0 liter. If I had it to do again I would do the heads and cam C6Z. I’ve been very blessed to have flipped and experienced all except the C8. Anyway you go you will not be disappointed! Pick the body style you like, you can make them all fast. The C5Z is very light and nimble with limited tech, which as I’ve gotten older I really appreciate, simple and effective!
Last edited by RWE 427; Sep 5, 2023 at 10:41 PM. Reason: Spelling
Drifting
Joined: Jul 2012
Posts: 1,325
Likes: 239
From: Missi'ppi... no mo' MO for me!!
Move up the c6z. There's no comparison whatsoever between a "z" and a base car. The c5z would trounce a base c6; the way they drive one would think the c5 z06 was the more advanced newer version of the Corvette. But a c6 z06 is that much more of a car over its' base version, and goose-steps over a base c5. You can't alter the offerings in a c5 base model to approximate a c5 z06 much less a c6 z06. The base c5's suspension, brakes, wheels, exhaust, engine are all "weaker" than the same year's Z version, and a step up in generation in a bone-stock c6 z06 would hold its' value MUCH better than a modded base c5 almost no matter how capable you can make it after the mods.
Le Mans Master
Joined: Dec 2013
Posts: 6,337
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From: Charles Town WV
2024 Corvette of the Year Finalist - Modified
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If you go the C6z route make sure you do your research on the head issues. Youll likely end up spending more money to fix it unless you buy a car thats already fixed. You can gamble and hope it doesn't happen to you but 5 grand in insurance by doing the heads or 25-30k replacing an LS7... also keep in mind things like tires and brakes are going to increase your maintenance cost in going to a Z. I loved my c5, but the c6 was an upgrade for sure. For the price youll be paying for a c6z I wouldn't count out a Grand Sport either, little less money, lot less potential problems... bullet proof LS3 (dry sump if you go manual coupe). An H/C/I c5 is def a well performing car though if you spend the money and do it right. The question you have to ask yourself is will you stop at that or will you want more.
Le Mans Master
Joined: Dec 2017
Posts: 5,590
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From: Virginia
2021 C5 of the Year Finalist - Modified
St. Jude Donor '21-'22
The answer to this question really depends on what YOU want. As many others have said, buying the C6 Z06 is 100% the correct choice financially. However, that's not the only factor. Years ago, I was deciding between selling my stock C5 and buying a C7. The other option was to keep the C5 forever, and mod it into the perfect car for me. I opted to med the C5. I like the way the C5 looks more. I think it is a timeless design that will look great forever. I love the car. As such, I accepted that I would never get back a dime that I put into the car. However, that doesn't really matter to me, because I'm never going to sell it. Everything that I do to the car is to make it the best car for me that it can be. If you don't truly love the C5 and want to keep it forever, the clear answer is to sell it for a C6 Z06. However, if you're like me, and you just plain love the C5, then maybe it's worth it for you to keep it and upgrade it. It certainly isn't the right choice financially, but it might be the right choice to make you happy.
Le Mans Master
Joined: Jun 2016
Posts: 5,426
Likes: 3,972
From: Cincinnati, OH
Another option...drop a LS7 into your C5. Aside from interior/exterior styling the cars are not much different if you are looking at them from a "weekend warrior/nice day cruiser/car show fanatic" glasses. If you want to race them and push them to the limit, then there are worthwhile differences.
That way you get the power of a C6Z at a massive discount compared to buying one.
I hate C6 interior styling compared to C5. Way too boring.
That way you get the power of a C6Z at a massive discount compared to buying one.
I hate C6 interior styling compared to C5. Way too boring.